Analysis: Citation Encore

Analysis
The third generation 560 offers almost unbeatable climb performance,
increased fuel efficiency, more tanks-full payload . . . and soft landings.
By Fred George
Photos by Paul Bowen
hortly after departing Wichita Mid-Continent Airport in
the Citation Encore, a glance at the rate of climb on the
PFD almost forced a double take. The aircraft was climbing in excess of 5,500 fpm, and we’d launched only 630 pounds
below MTOW. Granted, it was unseasonably cold, but, even if it
had been a standard day, the Encore’s initial climb rate would
have exceeded 4,800 fpm at that weight.
Loaded to its 16,630-pound MTOW, the Encore can climb to
FL 450 in 28 minutes in standard day conditions. And climbing
from FL 370 to FL 450, the Encore may have no equals among
current production business jets.
The Ultra, the Encore’s Model 560 predecessor, was no slouch
either, but a typically equipped Ultra only could carry three-plus
S
38 Business &CommercialAviation ■ March 2001
p a s seng ers with full fuel. And its Pratt & Whitney Canad a
JT15D-5Ds won no prizes for fuel economy.
By comparison, the Encore can carry four-plus passengers with
full fuel and offers slightly more range than the Ultra. New 2.55:1
bypass ratio turbofan engines make
it 12 .9 dB quiet er on take o ff an d
burn up to 10 percent less fuel en
route.
And fina l l y, Cessna fitted this
third-generation CE 560 with trailing-link main landing gear, thereby
eliminating the Citation V/Ultra’s
n o t o r io us plunk - d own arr i v a l s .
This Citation may offer the softest
landing touchdown characteristics
of any new gener at ion 500 - ser ie s
aircraft we’ve flown.
www.AviationNow.com/BCA
The 3,400-pound-thrust PW535 turbofans offer 12-percent more takeoff thrust, eight-percent more
cruise thrust and 16-percent better fuel economy.
More Thrust Mostly
Yields Improved Performance
Continuing Cessna’s nearly 30-year partnership with P&WC, the Encore is fitted
with new generation 3,400-pound-thrust
PW535A turbofans. The new Pratts provide a nearly 12-percent increase in takeo ff thrust and eight-perc ent boost in
high altitude cruise thrust. Just as importantly, the engines are up to 16-percent
more fuel efficient, in part due to their
having improved fan aerodynamics and a
h i g her cycle pre s sure rat io than the
JT15D-5Ds.
Cessna lengthened the wing 29 inches to
take advantage of the PW535A’s increased
high-altitude thrust, enabling the Encore
to climb to a higher initial cruise altitude
than the Ultra and get better fuel economy.
T he Encore also has aero d y na m i c
re f i ne m ents associated with its ne w
engines and landing gear. The PW535A
engines, being bigger than the JT15D-5D
turbofans, require wider and longer engine
nacelles. The engine pylons, as a result,
have been widened, lengthened and positioned farther away from the fuselage to
reduce interference drag.
Originally the Encore lost 477 pounds
of wing fuel capacity because of the larger
wheel wells associated with the trailinglink landing gear, but Cessna redesigned
and enlarged the tanks. Even though the
final production Encore has 344 pounds
less fuel than the Ultra, it has slightly
greater range.
The fuel tank redesign caused the certification to slip from early 1999 to April
2000. The first customer delivery occurred
in late September 2000.
The Encore doesn’t beat the Ultra in all
a reas. De s pite having a slightly bet t er
t h rus t - t o - weight rat io and 33 - perc ent
www.AviationNow.com/BCA
more powerful wheel brakes, the Encore’s
takeoff field length distances are longer.
This is due in part to the PW535 A’s
increased thrust. More thrust incre a se s
VMCG minimum control (ground) speeds,
thereby increasing all the takeoff V speeds.
More thrust also results in higher nosedown pitch forces at rotation, thus slowing
the rotation pitch rate.
The trailing-link landing gear design
also boosts take o ff distance. The mai n
gear axles are positioned farther aft, closer
to the horizontal stabilizer. This reduces
the length of the lever arm from the elevator to axle pivot point, thus increasing the
pitch force and dec re a s i ng the ro t at ion
rate on takeoff.
The result is the Encore’s having up to
10- to 31 - perc ent long er take o ff fie l d
lengths than the Ultra. At a 16,000-pound
takeoff weight, for example, the Encore’s
TOFL is 3,200 feet at a sea-level airport
on a standard day. The Ultra, by contrast,
needs 3,070 feet.
Hot and high con d i t ions wid en the
takeoff performance differences. When
d e p a rt i ng from As pen, Co lo., at 16,000
pounds, for example, the Encore is runway limited to ambient temperatures of
73°F (23°C) or below. A 16,000 - p o u n d
Ultra, by contrast, can launch with temperatures as high as 86°F (30°C).
After departing from a hot and high airport, though, the Encore has substantially
better climb than the Ultra. The Encore
may be runway length limited, but it’s
usually not limited by second-segment,
one - eng i ne - i n o per ative (OEI) climb
performance.
Structure and Systems
The wing shape remains unchanged. It’s
Cessna’s slightly modified NACA 23000-
series airfoil having a larger leading-edge
radius and a flatter top surface. The result
is a more even pressure distribution over
the length of the chord, a milder shock
wave and a slightly higher critical Mach
number.
T he mild ai rf o il re s h a pe produces as
much as a 0.08 Mach or 46-knot increase
in wing cruise speed. When coupled with
t he Encore’s higher thrust eng i nes, the
result is cruise speeds as high as 438 knots
at FL 290 and consistent 400-plus-knot
cruise speeds in the low to mid 40s.
Bo u n d a ry layer energ i z ers have been
added to the Encore’s wing leading edges
to improve its han d l i ng character i s t i c s
d ur i ng aero d y namic stalls. Cessna also
added a small chord-wise wing fence. As a
re sult, the Encore has less ten d ency to
drop a wing during stalls.
Pa s seng ers ent er the cabin through a
vault-design, forward entry door, measuring 50.7 inches high by 23.5 inches wide
near the bottom. The doorway has a sturd ily built, two-sec t ion board i ng lad d er
with solid treads and risers — friendly to
passengers wearing high heel or platform
shoes. When extended, the bottom step is
close to the ground for ease of boarding,
especially from wet or slippery ramp surfaces. The ladder has a damper on each
section, thereby allowing it to free fall at
a slow rate from the stowed position .
Two cables help steady the ladder when
extended.
The sturdy, two-section boarding ladder has solid
treads and risers to ease passenger boarding.
Business &CommercialAviation ■ March 2001 39
Analysis
The Encore’s new, trailing-link landing gear finally
c u r es th e Mo d el 5 60’ s n ot ori o us ly fi rm
touchdown thump.
A 35 - i n c h - w ide clamshell door is
offered as an option. There is a Type III
e m erg ency exit on the right side of the
f uselage, immediately across from the
main entry door.
The Encore retains the 500-series systems simplicity. The fuel system has leftand right-side wet wing tanks that feed the
respective engines. A single-point pressure
refueling receptacle aft of the right wing
root, standard equipment on all Model
560 ai rcraft since serial number 310, is
used to fill the tanks. Alternatively, overwing refuel ports can be used.
Oper ators can say goodbye to Prist.
Newly certified fuel heaters eliminate the
need to mix ant i - i c i ng additives with
t he fuel. Some oper ators, though, may
w ant to use a bio c idal additive to inhibit bacterial growth in the fuel cells,
e s pecially if the ai rcraft will be flow n
infrequently.
Under normal operations, a series of jet
pumps in the wing fuel tanks, powered by
motive flow pre s sure su pp l ied by the
engine-driven fuel pumps, supplies fuel to
t he eng i nes. DC - p owered fuel boost
pumps provide fuel for engine start and
for cross feed, and they provide backup to
the jet pumps.
Cessna retained the familiar color-keyed
circuit breakers on the left- and right-side
cockpit panels, plus the green ice protection systems switches on the left side of
the instrument panel.
Each wingtip leading edge has a recognition light and a landing light, controlled
by thre e - p o s i t ion switches. The mai n
landing gear struts also have landing lights.
Logo lights illuminate the vertical fin.
The PW535A engines produce enough
bleed air for full wing leading edge antiice protection, but quick cycling deice
boots are retained on the horizontal stabilizer leading edges. Bleed air also is used
for windshield anti-ice protection and rain
removal. Electrical heat is used for anti-ice
on the air data and angle-of-attack sensors.
The engines also produce bleed air for
cabin pressurization and air-conditioning.
The Encore has a new set-and-forget digital pre s sur i z at ion cont ro l ler. The cre w
need only set in landing field elevation and
the pressurization controller takes care of
the rest.
Similar to most Model 500 Citations,
Encore Flying Impressions
The aircraft we flew for this report, 560-0539, was the first Encore off
Cessna’s assembly line. The cabin was fitted with optional high-gloss
wood laminates on the cabinetry, 117 VAC cabin power outlets, MagnaStar
2000 radio telephone, passenger briefing system and various other
upgrades.
The middle passenger seats are the only seats that can be adjusted fore
and aft and turned 180 degrees.Thus,they can be adjusted to form forward
club or aft club seating configurations.
Additionally, the permanently mounted seats now have a small fascia at
the base that gives technicians access to a single bolt to release the seat for
removal. Said Bill Plucker, Cessna customer service supervisor, “Every
mechanic that I have showed this to has said, ‘It’s about time you did that.’”
Optional avionics included the Universal UNS-1Csp FMS with data transfer
unit, ordered by 85 percent of Encore buyers, plus Honeywell TCAS II and
Enhanced GPWS, also popular options. The aircraft also was fitted with the
optional ski tube, Pulselight system, plus provisions for a second ADF receiver and an HF radio.
This boosted the BOW to 10,607 pounds, 82 pounds above the B/CA
equipped weight, resulting in a full-tanks payload of 792 pounds. The retail
price was $7,258,650, $99,650 above the B/CA equipped price.
Preflight chores on the Encore are straightforward. Check brake fluid and
backup windshield deice alcohol levels, plus emergency oxygen and pneumatic system pressures by looking through small windows on the aft side of
the forward luggage compartment. Air data and angle-of-attack sensors can
be easily seen for visual inspection. The new trailing-link landing gear, being
slightly longer than the straight leg versions, increase the clearance between
the ramp and wing and fuselage bottom, thereby making it easier to sample
the fuel drains. Engine oil now can be checked by means of sight glasses
rather than dipsticks.A pop-up door inside the aft baggage compartment provides excellent access to the engine fire bottles, electrical junction boxes,
hydraulic reservoir, air cycle machine and vapor-cycle air conditioning system.
Demonstration pilots Gary Read and Stephen Stilling were on board for the
40 Business &CommercialAviation ■ March 2001
evaluation flight, with Read in the right seat and Stilling on the right forward
passenger seat as safety pilot.
Starting the Encore is easy. After completing the prestart checks, press the
right engine start button to initiate the automatic start sequence. At 10-percent N2, I advanced the thrust lever to idle, initiating fuel boost and ignition.
At approximately 38-percent N2, the starter disengaged, fuel boost and ignition were terminated, while the engine continued to accelerate to 49 percent
idle speed. The right generator came online automatically as the engine
approached idle speed.
I flicked the high idle switch to accelerate the right engine to 53-percent
N2 in preparation for starting the left engine. The Encore, similar to other 500series Citations, uses a generator-assisted cross-start system to ease battery
load during the second engine start. The left engine, as a result, started slightly faster than the right engine. Both engines were burning a total of 540 pph
at idle.
During taxi, we checked operation of speed brakes, flaps and thrust
reversers. ATIS said the OAT was -1°C, the wind was 350/28G33 and the sky
was clear. Based on a takeoff weight of 16,000 pounds, Read computed our
no-wind takeoff distance at 3,300 feet, with V speeds of 97 KIAS for decision
speed, 102 KIAS for rotation and 112 KIAS for the takeoff safety speed.
The initial rotation force on the yoke was decidedly heavier than in the
Ultra, but once airborne, the Encore’s pitch force was moderate and well balanced with roll control force. With three intermediate level-offs for air traffic
control and a decided shift to warmer than standard temperatures above FL
330, we reached FL 450 at ISA+8°C in 32 minutes, having burned 850
pounds of fuel. The time to climb to FL 450 was six minutes longer than
Cessna predicted as a result of the warmer than standard temperatures during the critical last 12,000 feet of the climb.
At level-off, we noted the Encore has a few quirks. First, the crew cannot
set an airspeed bug on the PFD IAS tape during cruise. The speed bug only
is available if the Primus 1000 avionics system is in a vertical speed mode,
such as flight level change or IAS hold. Second, direct sunlight washes out
www.AviationNow.com/BCA
the Encore uses an air cycle machine for
cabin refrigeration. The ACM, though,
isn’t very effective at cooling the cabin on
w a rm days, so Cessna also fitted the
E n c o re with an electrically powere d ,
vapor-cycle air conditioner, as it did with
t he Ultra. The vapor cycle system also
may be powered by a ground power cart,
thereby enabling the cabin to be cooled
prior to engine start.
The vapor cycle system has front and
rear evaporators in the cabin, but a single
z one therm o s t at. Airf low bet we en the
c o c k pit and cabin can be modulated to
produce comfortable temperatures in both
locations.
An on-demand, open center hydraulic
system pressurizes momentarily to 1,500
psi when needed to power the lan d i ng
g e a r, flaps, speed brakes or thrus t
reversers. Cessna has used the open center
hydraulic system design in Citat ion s
for almost three dec ades. Most of the
time when the hydraulic system isn’t in
use, the fluid circulates at very low pressure, thereby minimizing the possibility of
leaks.
The primary flight controls are manual-
The Encore’s standard center club seating optimizes legroom for four passengers.
ly operated with console-mounted trim
wheels in all three axes. Electric pitch trim
is available through conventional fail-safe,
split switches on the left and right yokes.
A flap position com pen s ated ang le - o f attack system provides an accurate indication of wing performance throughout the
the contrast on the Primus II radio management unit CRT displays in the
instrument panel, but the PFDs and MFD remain quite viewable in bright
ambient light. And finally, there is quite a bit of hysteresis (i.e., slop) in the
throttle linkage, making it difficult to set thrust precisely. Cessna is redesigning the linkage.
At FL 450, the aircraft accelerated to 367 KTAS on a fuel flow of 850 pph
at a weight of 15,400 pounds. Both the cruise speed and fuel flow were lower
than book, owing to the warmer than standard outside air temperature.
Cruising at 166 KIAS at FL 450, the Encore had very modest low-speed buffet margins. A slight increase in g loading produced noticeable airframe rumble. Conclusion? While the Encore has enough thrust to climb directly to FL
450 at MTOW, operators should note that high altitude turbulence may cause
intermittent high angle-of-attack wing buffet and subsequent airspeed loss.
Checking the high-speed cruise performance at FL 370, the Encore
achieved 428 KTAS on 1,230 pph at a weight of 15,200 pounds in ISA+7°C
conditions. This was three knots faster and 100-pph less fuel flow than the
book predicted for the same weight in standard day conditions. We noted that
the Encore has wide high-speed buffet margins at 0.73 Mach, near its 0.755
IMN redline. At indicated airspeeds of 190 to 200, or greater, there was plenty of low-speed buffet margin.
Extending the landing gear causes a modest ballooning. Cessna refined the
flap/pitch trim interconnect system, though.The pitch change associated with
extending the wing flaps is almost non-existent. Yaw damping is excellent.
The Encore’s stall behavior is much improved over the Ultra. The clean stall
is preceded by ample airframe buffet and the stall-warning stick shaker. At full
stall, the nose gently falls with no sign of wing roll-off.
Dirty stalls are almost as pleasant. The pitch force increase preceding the
stall is lighter and there is a slight tendency for wing roll-off at the full stall.
However, the roll is easily corrected with aileron.
Descending into Hutchinson for pattern work, the reported wind was 20
knots gusting to 30 knots, 30 degrees off runway heading, with patches of ice
on 7,001-foot-long Runway 31. This would be an excellent test of the
Encore’s handling manners and trailing-link landing gear.
At a landing weight of 14,700 pounds, the computed VREF was 106 KIAS.
www.AviationNow.com/BCA
flight envelope. A three o’clock angle-of
attack reading, for example, indicates optimum V 2 or V R E F w i ng perf o rm an c e
regardless of weight. The angle of attack
system also activates a stall warning stick
shaker at high angles of attack.
Bungee linkages in the rudder pedals
We flew the initial part of the final at VREF+10, slowing to VREF over the runway. Wing down, top rudder technique requires some hefty torque on the yoke
because of the Encore’s aileron/rudder interconnect system, but the aircraft
responded well to control inputs.
Touching down on the upwind main landing gear with no particular finesse,
the Encore rewarded us with a generously soft arrival. The four-foot narrower
track made it much easier to control the Encore’s subsequent roll to wings
level and touchdown of the downwind landing gear. A combination of moderate thrust reversing and wheel braking brought us to a stop in 3,500 feet.The
anti-skid system proved to be quite effective.
OEI conditions are easy in the Encore. The V speeds are relatively slow; the
thrust reserves are quite ample. Departing from Hutchinson, for example, the
aircraft climbed at 2,500 fpm at V2+10. Asymmetric pedal forces are heavy,
but controllable. The Encore has more thrust than the Ultra and the same rudder system. The result is more rudder pedal force.
No-flap landings also are easy in the Encore. Just add 15 knots to the normal VREF and plan to fly a longer final approach. Predictably, the pitch attitude
was more nose-up. With little drag, we used little more than idle thrust levels
on final at a 121 KIAS VREF. The Encore’s effective anti-skid braking system,
coupled with ample use of reverse thrust, brought us to a stop within 4,500
feet of runway.
Pattern work revealed another quirk in the Encore’s avionics package .T h e
flight director cannot be permanently deselected. If the aircraft deviates from
a pre-set altitude, the flight director automatically pops back into view. It must
be manually deselected each time this occurs until the altitude deviation
exceeds 300 feet from the pre-set altitude.
Arriving at Wichita at a landing weight of 13,800 pounds, our computed
VREF was 104 KIAS. For landing on Runway 01R, the wind was 350 at 28
gusting to 40 knots. The wind dropped off sharply, just prior to touchdown,
creating a 10-knot loss in indicated airspeed. A sharp tug on the yoke,
though, arrested the rate of descent. Touchdown in stick shaker was quite
soft, much softer than we deserved.
Total flight time was one hour, 57 minutes and total fuel burn was 2,240
pounds.
Business &CommercialAviation ■ March 2001 41
Analysis
Cessna Citation Encore
These three graphs are designed to be used together to provide a broad view of the Encore's performance. Do not use these data for flight planning. For a complete operational analysis, use the Approved Aircraft Flight Manual, Operational Planning Manual and other flight-planning data supplied by Cessna Aircraft Co.
Time and Fuel vs. Distance — This graph shows the performance of the Encore at 358 to 378 KTAS Mach long-range cruise and 400-plus KTAS high-speed cruise.
The numbers at the hour lines indicate the miles flown and the fuel burned for each of the two cruise profiles. Each of the hour points is based upon specific mission data supplied by Cessna. While flying the Encore for this report, we found Cessna's flight-planning data to be accurate, if not somewhat conservative.
Specific Range — The specific range of the Encore, the ratio of miles flown to pounds of fuel burned (nm/lb), is a measure of fuel efficiency. The lines on this chart,
being based on four data points between long-range and high-speed cruise, are approximations of the change in specific range between the endpoints. Similar to
other turbofan aircraft, the spread between the Encore's long-range and high-speed cruise specific range narrows at maximum cruise altitude.
Range/P ayload Profile — The purpose of this graph is to provide simulations of various trips under a variety of payload and airport density altitude conditions,
with the goal of flying the longest distance at high-speed cruise. The five payload lines are plotted from individual mission profiles with four to five data points, ending at the maximum range for each payload. The time and fuel burn dashed lines are based upon the high-speed cruise profile shown on the Time and Fuel vs.
Distance chart. The runway distances, computed using FAR Part 25 rules, are based upon a flaps 15-degree configuration for both sea-level ISA and B/CA's 5,000
feet, ISA+20°C airport.Notably, the Encore can depart at MTOW from B/CA's hot-and-high airport at up 39°C (102°C) using the flaps 15-degree configuration.
42 Business &CommercialAviation ■ March 2001
www.AviationNow.com/BCA
pro v ide up to 20 deg rees of nose w he e l
steering. Differential thrust and braking
can be used to increase nosewheel steering
authority up to 95 degrees.
T he electrically cont ro l led and hydraulically actuated wing flaps have four
detents: retracted, seven degrees (takeoff),
15 deg rees (take o ff and approach) an d
35 deg rees, full down for lan d i ng. The
electrically controlled and hydraulically
a c t u ated speed brakes have two positions — extended and retracted.
An emergency pneumatic blow-down
bottle provides power to extend the landing gear and for emergency wheel braking. In contrast to the Ultra, the blowdown bottle will release the Encore’s landing gear up locks.
About 10 percent of Encore customers
continue to opt for Cessna’s gravel runway kit. The kit consists of a nosewheel
s pin-up system to pre v ent debris from
b e i ng kicked up into the eng i nes on
touchdown, plus antenna guards and wing
flap shields.
s t r at o r, slated to go on the market in
December 2002. Want a new non-demonstrator? The first position is in February
2003.
The B/CA Comparison Profile shows
no clear explanation for the Encore’s success. When stacked up against all light jet
competitors, plus the Citation Excel and
Learjet 45, the Encore’s price matches the
c omposite average within 0.2 perc ent .
The Encore has an edge in cabin length,
but not cabin width or cabin height. It’s
not the fastest, it doesn’t have the most
range and it’s not the most fuel-efficient
aircraft in the group.
The Encore, though, offers versatility. It
can fly a ton of payload more than 1,000
m iles or four passeng ers almost 1, 600
m iles. It can oper ate out of 4,000 - f o o t
runways on most missions, yet climb
d i rectly to FL 450 at MTOW. Its re l a tively high 15, 400-pound max lan d i ng
weight enables it to fly multiple unrefueled legs. The Encore can cruise at 0.74
Mach, providing it with very competitive
block times on typical 600-mile business
trips.
What’s not on the Comparison Profile
may have more to do with the Encore’s
success than the bar graph indicat e s .
C i t at ion oper ators have long pr ai se d
Cessna for superior product support. The
Encore is easy to fly and its low V speeds
make it one of the most-docile airplanes
Comparison Profile
(Percent Relative to Average)
Price vs. Performance
At a B/CA equipped price of $7,159,000,
the Encore remains the most expensive
offering in the light jet class, just $1.6 million less than the midsize cabin Excel. The
Learjet 45A costs only $1.8 million more.
Yet, Cessna has 100-plus aircraft on back
order. The next available slot is a demon-
Encore Operating Costs
Annual Fixed Costs
Captain............................................$61,000
Copilot................................................37,300
Benefits Package @ 25%....................24,575
Hangar*.............................................12,000
Insurance — Hull @ 0.3%* .................21,477
Insurance — Liability and Medical* ......4,500
Recurrent Training*.............................17,600
Aircraft Refurbishment........................25,000
Navigation Chart Service......................2,500
CESCOM*.............................................1,000
Weather Services..................................1,000
Fair Market Depreciation ..............................0
TOTAL.............................................$207,952
Hour ly Direct Costs
Fuel @ $2.25/gallon*......................$405.00
Maintenance — Labor*.........................58.50
Maintenance — Pro Parts*...................83.26
Engines Reserves*.............................147.52
Thrust Reversers....................................10.00
Landing/Parking Fees...........................20.00
Miscellaneous Crew Expense................50.00
Small Supplies and Catering ................10.00
TOTAL................................................$784.28
Tradeoffs are a reality of aircraft design, although engineers attempt to optimize the blend of capabilities,performance and passenger comfort.
In order to portray graphically the strengths and compromises of specific aircraft, B/CA compares the
subject aircraft to the composite characteristics of other aircraft in its class, computing the percentage differences for the various parameters. We also include the absolute value of each parameter,
along with the relative ranking, for the subject aircraft within the composite group.
For this Comparison Profile, B/CA includes the Bombardier Learjet 31A, Bombardier Learjet 45,
Citation Bravo, Citation Encore, Citation Excel and Raytheon Beechjet 400A. The Encore's retail price
is within 0.2 percent of the composite average, but its performance and cabin specifications distinguish it from the composite mix.
*Cessna estimate
www.AviationNow.com/BCA
Business &CommercialAviation ■ March 2001 43
Analysis
around the airport. The cockpit is a model
of erg on omic design. In spite of its
s prightly take o ff and lan d i ng perf o rmance, turboprop pilots should find it easy
to transition into the Encore. It’s much
easier to handle during OEI conditions
than a turboprop, in our opinion. It also
o ff ers bet t er OEI climb perf o rm an c e
t h an some tur b o props can with both
engines.
The Encore’s trailing-link landing gear
makes for soft touchdowns and smooth
taxi rides. The Honeywell Primus 1000
avionics suite is highly intuitive and easy
to use. The Encore shares a common type
rating with the Ultra and Citation V, and
with all 500-series Citations except for the
CJs and the Excel. The Encore is eligible
for the FAA’s single-pilot waiver, thereby
enabling one pilot to fly the aircraft when
essential. From a pilot’s perspective, the
Encore simply feels as comfortable as they
come.
The Encore is aptly named. This aircraft, as much as any business jet in history, owes its success to re pe at bus i ne s s .
Most buyers trade in older Citations for
E n c o res. For them, the Encore off er s
m o re perf o rm ance, but the theme is as
familiar as a new arrangement of a favorite
ballad.
Perhaps all these factors help explain
why the light jet market is saying
“Encore!” about the third Model 560. B/CA
Honeywell Primus 1000 Avionics
The Encore inherits the Ultra’s very capable Honeywell Primus 1000 avionics package, which embraces
the familiar hub-and-spoke architecture. The three eight-by-seven-inch CRT displays — left- and rightside PFDs and a central MFD — are the most visible elements of the system. The MFD is flanked by
twin Honeywell Primus II radio management units.
The Encore’s annunciator panel has been moved to the glareshield, thereby making the instrument
panel less crowded. The move also makes space available on the instrument panel for annunciator
lights associated with optional avionics equipment.
Twin IC-600 integrated avionics computers form the hubs of the system. Honeywell uses its ASCB
local area network, ARINC 429, a proprietary radio systems bus and analog interfaces to form the
spoke links to the central computers.
The standard package includes dual DADCs, dual analog vertical and directional gyros, dual DME
radios, single ADF, 10 kW Primus 660 weather radar, basic single waypoint vertical navigation,
Honeywell AA-300 radio altimeter, pilot’s side angle-of-attack indicator, Loral/Fairchild CVR, Artex ELT
and a single Honeywell GNS-Xl navigation management system.
Popular options, with incremental weight and price change, include Universal UNS-1Csp FMS (4.7
pounds and $10,075), Honeywell TCAS I (79.2 pounds and $87,350) or TCAS II (83.4 pounds and
$152,425), Honeywell E GPWS (20.5 pounds and $82,275), Fairchild FDR (40.2 pounds and
$32,250) and Teledyne Controls MagnaStar C-200 digital radio-telephone (30.6 pounds and
$53,900).
Other options include Rockwell Collins Pro Line II radios (-14.3 pounds and no charge),Honeywell
KHF-950 transceiver (32.2 pounds and $28,925), Honeywell AFIS (23.5 pounds and $49,475),
Universal Unilink (12.4 pounds and $31,275) and JAA specification Honeywell FDR (51.7 pounds and
$128,025).
Cessna Citation Encore
Specifications
B/CA Equipped Price . . . . . . . $7,159,000
Characteristics
Wing Loading . . . . . . . . . . . . . . . . . . . 51.6
Power Loading . . . . . . . . . . . . . . . . . . 2.45
Noise (EPNdB) . . . . . . . . . 70.0/89.8/90.5
Seating . . . . . . . . . . . . . . . . . . . . . 2+7/11
Dimensions (ft/m)
External
Length . . . . . . . . . . . . . . . . . . 48.9/14.9
Height . . . . . . . . . . . . . . . . . . . 15.2/4.6
Span . . . . . . . . . . . . . . . . . . . 54.1/16.5
Internal
Length . . . . . . . . . . . . . . . . . . . 17.3/5.3
Height . . . . . . . . . . . . . . . . . . . . 4.7/1.4
Width . . . . . . . . . . . . . . . . . . . . 4.9/1.5
Thrust
Engine . . . . . . . . . . . . . . . 2 PWC/PW535A
Output . . . . . . . . . . . . . . . . . . 3,400 lb ea.
Flat Rating OAT°C . . . . . . . . . . . . ISA+12°C
Inspection Interval . . . . . . . . . . . . . . 5,000
Weights (lb/kg)
Max Ramp. . . . . . . . . . . . . . 16,830/7,634
Max Takeoff . . . . . . . . . . . . . 16,630/7,543
Max Landing . . . . . . . . . . . . 15,400/6,985
Zero Fuel . . . . . . . . . . . . . . 12,600/5,715c
BOW . . . . . . . . . . . . . . . . . . 10,525/4,774
Max Payload . . . . . . . . . . . . . . . 2,075/941
Useful Load . . . . . . . . . . . . . . 6,305/2,860
Executive Payload . . . . . . . . . . . 1,400/635
Max Fuel . . . . . . . . . . . . . . . . 5,431/2,463
Payload w/Max Fuel . . . . . . . . . . . 874/396
Fuel w/Max Payload . . . . . . . . 4,230/1,919
Fuel w/Executive Payload . . . . 4,905/2,225
Limits
MMO. . . . . . . . . . . . . . . . . . . . . . . . . 0.755
FL/VMO . . . . . . . . . . . . . . . . . . FL 289/292
PSI . . . . . . . . . . . . . . . . . . . . . . . . . . . 8.9
Climb
Time to FL 370. . . . . . . . . . . . . . . . 13 min.
FAR Part 25
OEI rate (fpm/mpm) . . . . . . . 1,440/439
FAR Part 25
OEI gradient (ft/nm). . . . . . . . . . . . . 873
Ceilings (ft/m)
Certificated . . . . . . . . . . . . 45,000/13,716
All-Engine Service . . . . . . . 45,000/13,716
Engine-Out Service. . . . . . . . 32,500/9,906
Sea Level Cabin . . . . . . . . . . 23,586/7,189
Certification . . . FAR Part 25, 1988/94/00
44 Business &CommercialAviation ■ March 2001
www.AviationNow.com/BCA
Shop Talk
By Dave Benof
f
➤Emergency
lighting.
lighting power.
➤Speed brakes.
➤ Thrust reversers.
➤Landing/taxi/recognition lights.
➤Secondary flight display.
➤Engine anti-ice — Same as Ultra except controlled by different personal computer board (PCB).
➤Air conditioning — Same as Ultra except controlled by
different PCB.
➤Wiring — Same as other Citations in type and routing
practices.
The following is a summary of all the modifications and
their impact on the maintainability of the aircraft.
➤Emergency
The Encore incorporates three major modifications that affect maintenance.
Out of all the changes that Cessna made to improve the
Encore, the most important one was to provide maintainers
with a voice in the design process.
“We never had someone from the maintenance field who
gets feedback from the technicians go back to the design
program group and say, ‘Look guys, this isn’t working and
you can’t do this on this airplane,’” said Bill Plucker,
Cessna’s customer service super visor, a new position created to help ensure the aircraft’s maintainability. “As a field
ser vice technician with an A&P license and an engineering
background, I translate the wants and needs between the
two parties.”
During an effort to incorporate engineering changes into
the Ultra, Cessna decided to seek a new certification called
a Block Point Change (BPC) on serial numbers after 560-568.
The newly certified aircraft, now called the Encore, incorporates three major modifications that affect maintenance.
First, the PW535A engines provide improved specific fuel
consumption and increased maintenance periods, which both
contribute to greatly reduced direct operating costs (DOCs).
Second is the trailing-link landing gear. And third, the new
outboard wing leading edge anti-icing system enhances durability and reduces DOCs over the old deice system.
Other design changes did not significantly alter any inspection intervals, although the Encore did inherit maintenance
tasks from equipment that was installed on other air frames
such as the Bravo and Excel.
Encore systems that are identical to the Ultra systems
include:
➤Cabin environmental system.
➤ Engine monitoring.
➤ Exterior lights.
➤ Flap system.
➤Generator control units.
➤Starter/generator units.
➤ Interior lights.
➤Pitot and static heaters.
www.AviationNow.com/BCA
Electrical Systems
The Encore’s trim system is similar to the Ultra’s but slightly modified with a latching circuit to prevent the wheel from
snapping back when the pilot releases the trim button at
high speeds.
The tail leading-edge deice circuitry has been modified to
cycle the stabilizer boots every three minutes. Lights on the
annunciator panel illuminate when one side is pressurized, or
the system fails to pressurize correctly. The angle-of-attack
indicator was taken directly from the Bravo and Excel and
incorporates a heater monitor directly into a controller. The
advantage to maintaining this angle-of-attack device is that
it can be completely removed and repaired from the exterior
of the aircraft. “Technicians wanted exterior access so they
did not have to remove interior components,” said Plucker.
One change that maintainers might not like is the completely modified J-Box assembly in the aft section. “The JAA
said we had to have a separate emergency busing system
and you will find this on all of the new Citations,” said
Plucker. “We also moved all of the circuit breakers and the
PCB boards into the J-Box assembly. This makes it more difficult to remove the J-box cover because of its size.” In order
The Encore’s revised co-breaker panel complies with JAR standards.
Business &CommercialAviation ■ March 2001 45
Analysis
to remove the cover you need to crawl all the way back into
the aft bay, above the air-conditioning unit, and detach five
Dzus fasteners (see photo above).
Landing Gear
Everything on the Encore’s gear, including the actuators, has
been beefed up except for the trunnion gear, which is common to both the Bravo and the Excel. The gear improvements
have added weight and, Plucker says, “eventually we will put
another gross weight increase on this aircraft.”
Jacking the aircraft can be easily accomplished by placing
a bottle jack under the main gear jack pads, which also
reduces the time it takes to service the wheel and brake
assembly.
The Encore uses four-disk heavy-duty Bendix brakes, with
a brake-metering valve instead of master cylinders for actuation. The brake metering valve is similar to those on the
Citation VII, X and CJ2 and is electrically driven by a
hydraulic power pack located under the nose avionics bay.
The squat switch also was modified with ramps on both
sides. “We learned the hard way that when people were taking the gear apart, they dropped the cam down, which
caused the switch to fall on the opposite side, and when they
picked the cam up it broke the switch, so we modified it,”
said Plucker.
The tire and wheel assembly, at this point in the service
test, had about 230 landings before replacement, but the
goal on any Citation is to get 300 landings out of a tire. “I’ve
gone back to the engineering group and said 230 is not good
enough; keep working on the tire,” said Plucker.
The high-pressure tire runs at about 150 psi and the wheel
assembly has a standard Excel, dual-channel operation, antiskid system. The Ultra utilized a system that released both
brakes whenever a skid was detected, but the Encore incorporates an individual wheel system where each brake is controlled separately.
The gear retraction system is still basically the same, with
hydraulic actuation and manual release.
Wing Anti-Ice System
The heated inboard leading-edge section of the wing is
unchanged from the Ultra, but to accommodate the wing antiice system, the wing forward fuel closeout was shifted aft.
The anti-ice system consists of a piccolo tube, which con46 Business &CommercialAviation ■ March 2001
trols the volume of air flow. A diffuser directs the airflow to
the backside of the leading edge skin to optimize heat transfer. The aluminum leading edge is fastened with posi-drive
screws. Cessna used this screw because the heads are relatively shallow. The problem is that they are susceptible to
over-torque. The shallow skin of the leading edge is countersunk only a little without going through the entire thickness.
“I have a change notice into engineering and it says find a
different screw,” Plucker told B/CA. “I don’t want customers
to over-torque these screws. On production these posi-drive
screws will be used, but after a while there will be a change
with a standard type Phillips.”
The boundary layer energizers on the leading edge are
steel so that when you polish the leading edge, you won’t
polish the energizers’ sharp corners that create the vortex.
To change the energizers you must remove the entire leading
edge and unscrew them from behind.
The wingtip is the same as the Excel’s and is easy to
remove because it is not deiced.
“Our operators have asked us to stop sealing the wingtip
lamp covers and we have taken it under advisement, but at
this point, for reliability purposes, we do not feel that that
would be a good idea,” said Plucker.
Fuel System
The fuel sump is inboard and forward on the wing with additional relocation of the fuel transfer pumps. Also, the saddle
tank containing the boost pumps, primary ejector pumps, the
transfer ejector pumps and fuel sump with added temperature
sensor are relocated. Aft of this tank in the dry bay area
Cessna has placed all of the shut-off valves that are accessed
through panels under the wing on the fairing.
Other fuel system changes include a new active capacitive
fuel gauging system, similar to the Bravo’s, and an additional transfer vent line added aft of the main spar to increase
pressure refueling rates.
Cessna also brought bypass air in from the engine through a
control valve into the ducting for flow over the precooler and
Cessna has 100-plus aircraft on back order. The next available slot is a
demonstrator, slated to go on the market in December 2002.
www.AviationNow.com/BCA
Floor mods have provided an additional two inches of seating height.
then overboard. The precooler is located at the top of the
pylon. At first look it appears that it might be difficult to reach,
but all of the structure around the lines can be easily removed
in about six pieces. After that, there’s ready access to the four
bolts that secure the precooler. Currently the maintenance
manual says to disconnect all of the lines and take the intercooler out, but Plucker says that’s erroneous and the manuals
will be changed later to reflect this procedure.
PW535A Engine
The Pratt & Whitney Canada PW535A produces 3,400
pounds of thrust, flat rated to 27°C. The engine’s core is
common to the PW545A and PW530A engine.
The integrally bladed rotor (IBR) is directional solidified
(DS) to improve efficiency and is very similar to that on the
Model PW545A, only smaller in diameter.
The fuel control is hydromechanically actuated and the
low-pressure turbine has one less stage than the PW545A. A
cookie-cutter forced mixer nozzle reduces exhaust noise and
improves high altitude thrust output, with one drawback.
“The engines are going to smoke and the tail cone is going
to get dirty. We know this is something that Citation owners
are not used to but that’s how it is with this engine,” said
Plucker.
In the inlet of the test aircraft there were three cracks that
Cessna said were caused by hand forming the component.
“It should have been riveted together like you tighten a tire.
What we did wrong was starting at one section and riveting
all the way around. On production aircraft we don’t anticipate
having any of those inlet problems because the production
internal design is different,” said Plucker.
Cessna also used to run an inch and one-half bleed air line
from the engine to the inlet ring. “We found that number one,
we did not need that much air and number two we were overpressurizing the assembly. So this one has been reduced to an
inch line and it passes all of the tests well and does not do as
much damage. So we do not anticipate nearly as much cracking down the road as we have seen now.”
Through holes in the inlet ring’s interior, bleed air passes
through the bulkhead at a lower temperature and heats the
aft nacelle area. Finally, through three-eighth inch holes in
the inlet area the bleed air exits and goes down the throat of
the engine. So there is no more running the engine and placing your fingers around the inlet lips to see if the bleed air is
www.AviationNow.com/BCA
working, because if you feel heat at the inlet you know it
is working. “It’s just safer to do it this way,” said Plucker.
The throttle system is similar to the Bravo’s, but the throttle switches are now located in the belly of the airplane and
not in the pedestal assembly. This makes them easier to get
to and adjust.
There is also no starter generator motor cooling air inlet. It
is now cooled with bypass air.
An engine vibration monitoring system, similar to the
Bravo’s, is installed and engine vibration trending can be
accomplished by Cessna, P&WC, a third party or directly by
the operator. The software is placed on a basic laptop computer and the flight information is easily downloaded.
It is thanks to the vibration program that this engine’s TBO
has been lengthened. Hot section inspection (HSI) is at
2,500 hours and overhaul is at 5,000 hours — an improvement of over 1,500 hours as compared to the JT-15D.
Traditionally, Cessna said you are going to find cracking on
the pylons on Citation aircraft. “These pylons are bigger and
there are more unsupported areas, so I expect to see some
cracking, but it is not going to be a tremendous hazard if you
see some. If we find there is a trend and how it cracks we
will do something about it,” said Plucker.
The Cost to Maintain
With better tracking of maintenance data and improvements
to the design, Cessna said it expects to improve MTBF numbers especially in the area of cables. Right now, since the
cost of the cables is not very much, operators typically
replace them because they have to break them down anyway. Under the five-year warranty period Cessna said the
maintenance cost per flight hour is as shown below.
Cessna’s ProParts PowerAdvantage program covers
engine parts, including rental and service bulletins, at a rate
of $60.43 per hour per engine. Engine reserves are estimated at $147.52 per flight hour; this includes hot section, overhaul and remove/install labor hours. It should be noted that
some consumables and transportation charges are not
included in these estimates.
Cessna did say that current operator support comes first.
“If we don’t have the part we have other avenues that we
can go to. Number one, we can go direct to the supplier and
say drop ship this part. If they don’t have it, then we will go
to the line and take a part off of the line. Availability of parts
for this aircraft will not be a problem,” said Plucker. BCA
Maintenance Cost Per Flight Hour
Scheduled
Inspections
MAN-HOURS
Repair &
Total
Replacement Man-Hours
LABOR DOLLARS
P ARTS
($65.00
(2000
per hour)
ProParts Prices)
Year 1
0.8
0.1
0.9
$58.50
$12.00
Year 2
0.8
0.1
0.9
$58.50
$50.05
Year 3
0.8
0.4
1.2
$78.00
$83.26
Year 4
0.8
0.4
1.2
$78.00
$83.26
Year 5
0.8
0.4
1.2
$78.00
$83.26
Out of
Warranty
0.8
0.5
1.3
$84.50
TBD
Business &CommercialAviation ■ March 2001 47