Systems Flashcards
The duchess has ___ propellers
Counter rotating. (so there is no critical engine)
In a plane with counter-rotating props (CRP), which way do they spin?
As viewed from cockpit, left prop spins clockwise and right spins counterclockwise/
Disadvantages of CRP
One propeller must have an additional reversing gearbox, or the engines themselves must be adapted to turn in opposite directions. (Meaning that there are essentially two engine designs, one with left-turning and the other with right-turning parts, which complicates manufacture and maintenance.)
In a single vs multi engine aircraft - what happens to your constant speed prop when you lose engine power?
Low oil pressure causes:
Single-engine aircraft - prop to low pitch, hi RPM
Multi engine aircraft - prop will feather
Describe the engines in the BE-76 Duchess (9)
4-cylinder Lycoming horizontally opposed direct drive (crankshaft connected to prop) 360 cubic inch carbureted 180 HP at 2700rpm piston driven normally aspirated
What model engines are on the Duchess?
Left O-360-A1G6D
Right LO-360-A1G6D
(Opposed, 360 cubic inch)
Describe the props on the Duchess (6)
Hartzell 2-bladed (Macauley actually?) controllable pitch constant speed full feathering aluminum alloy 76" normal (74" min fo rrepair) HC-M2YR-2CEUF/FC7666A (left) HC-M2YR-2CLEUF/FJC7666A (right)
Describe the landing gear on the Duchess (4)
Fully retractable
tricycle gear
Magnesium and Aluminum
hydraulically actuated
What keeps the gear up?
Hydraulic pressure of 1250-1550 +/-100
What keeps the gear down?
Springs assist in extension and lock the gear in the down position. Springs and hydraulic pressure hold the over-center brace/joints in position until hydraulic pressure is released by reversing the pump.
Where is the hydraulic fluid reservoir? Where is the motor (electric pump)?
Both are behind the baggage compartment
What is a squat switch?
Some planes have a squat switch which senses if the weight of the aircraft is resting on the gear. The usually fail in an always on (weight on the gear) state; so the gear will fail to retract rather than failing to extend
What prevents accidental gear retraction in the Duchess?
pitot tube (airspeed) switch for fault protection
Switch is open on the ground, preventing pump from receiving current
Switch closes at 59-63 KCAS
What extends/retracts the gear? What powers it?
electric reversible hydraulic pump.
What can you do during a hydraulic malfunction?
Pull gear motor circuit breaker. Open emergency gear extension valve (90deg clockwise) to release hydraulic pressure directly into reservoir and allow gear to free-fall down. Limited to 100 kts due to air-load on nose gear and corrosive hydraulic fluid returning to reservoir will overflow
Describe the brake system
hydraulically actuated disc brakes on main gear
wear down to 0.45 in
master cylinder for each set of pedals
reservoir inside nose section on left
Describe the flaps on the duchess
Plain flaps (no slots/slats). Electric motor beneath passenger seats. Settings 0-35deg
slots & slats:
https://www.boldmethod.com/learn-to-fly/aircraft-systems/leading-edge-slat-lift-device/
Describe the electrical system in the Duchess
28V single-wire, negative ground, DC system with push/pull circuit breakers
converter turns AC from alternator to DC
Describe the stall warning system on the Duchess
Two electric stall tabs
Left provides stall warning at 0-16deg flaps
Right provides stall warning at 16-26deg flaps
What’s the time delay relay? What is its purpose?
For the landing gear - pump stops after 30 seconds of operation, pilot must recycle gear lever to reset. So if there’s a leak and pump can’t maintain 1250 PSI, it won’t be continuously on.
Is the gear system protected by any circuit breakers?
2: gear motor and control
Landing gear retraction moment
1177 in/lb
Describe the gear down cycle
Current to pump Fluid to actuators Gear extends Switches turn on lights Pump off, system depressurized Over center gear and springs hold gear down
Gear up cycle
Check pitot switch for 59-63kts Send electricity to pump Pump sends fluid to actuators gear retracts at 1550 PSI, pump shuts off (on below 1250)
When does the gear warning horn go off?
throttle too low to maintain flight (12”) or flaps beyond 16
Tire pressure and Strut pressure
What gas is in the tires & strut?
all tires 38 PSI
nose gear 250
main gear 300
Nitrogen
Describe the oil system
6qt min, 8qt max.
Dipsticks not interchangeable
Oil cooler (thermostatically controlled)
1st 50 hours - MIL-L-6082C then MIL-L-22851
Describe the ice protection in the Duchess
Carb heat (unfiltered air) Pitot heat Windshield defrost
Cowl Flaps - max temp
CHT (cylinder head temp): max 500deg F
Starters - how long can you leave them engaged? How long do you need to wait afterward?
30secs, 2 mins off
How do you prime?
Push in the magnetos 10 sec
Where is the starter engaged warning light?
Between magnetos
Placeholder card for powerplant instrument markings on page 3 of BE-76 System and Limitations
Oil Temperature
Caution Range (Yellow Arc) – 60O – 120OF
Normal Operating Range (Green Arc) – 120O-245OF
Maximum – (Red Radial) – 245OF
Oil Pressure
Minimum Idle (Red Radial) – 25PSI
Caution Range (Yellow Arc) – 25-60PSI
Normal Operating Range (Green Arc) -60-100PSI
Maximum (Red Radial Line) 100psi
Manifold Pressure
Normal Operating Range (Green Arc) – 15 to 29.6 inHG
Tachometer
Normal Operating Range (Green Arc) – 2000-2700 RPM
Maximum (Red Radial Line) – 2700 RPM
Fuel Pressure
Minimum (Red Radial) – 0.5 psi
Normal Operating Range (Green Arc) – 0.5-8.0 psi
Maximum (Red Radial) – 8.0 psi
Cylinder Head Temperature
Normal Operating Range (Green Arc) – 200 to 500 OF
Maximum (Red Radial) – 500 OF
What kind of propellor governor does the duchess have? What does it do?
Woodward hydraulic L210650 and R210652
It sends oil pressure to/from the propeller hub
What keeps the prop from feathering on the ground in a SINGLE engine aircraft?
This is not an issue with single engine aircraft because low oil pressure keeps it at hi RPM mode, takes hi oil pressure to move blades toward higher pitch
What sends props to high pitch, low RPM (feather)?
Counterweights, Springs + nitrogen (40psi) act against oil pressure, dome pressure
https://youtu.be/Iprf3AOnus0?t=63
What sends props to low pitch / high RPM?
Oil pressure acts against (compresses) spring
What do props do during climb?
Underspeed: Flyweights in, pilot valve opens, oil into hub, sets low pitch / hi RPM.
What do props do during descent?
Overspeed: Flyweights (counterweights) out, pilot valve closes, oil exits hub to reservoir, nitrogen & spring push back, high pitch / low RPM
What prevents prop feathering on the ground?
A feathering lock. Centrifugal pins (latches) come out to prevent prop from feathering on the ground w no oil pressure and <700-800rpm. They retract when engine starts. when you shut engine down, prop will be at low pitch because below governed RPM and pins return to lock position and hold blades before spring can feather the blades
How do props feather?
Pilot valve opens, cuts off oil supply, letting oil drain out of propeller hub. Spring, counterweights, nitrogen, and aerodynamic load pushes blades to high pitch. Feathering latches engage
What are the pitch settings at 30” station?
Low 12.1 +/- 1
High 17-20
Feather 81 +/- 1
PN for Hartzell spinner assembly
C2285-3P and C2285-3PL
How does the throttle work on the duchess? Which gauge shows your throttle setting?
Same - you’re just opening/closing throttle valve. Your throttle setting is shown on the manifold pressure gauge
How do you change the RPM setting?
You choose an RPM setting with the prop control. The prop governor maintains that setting by sending oil pressure to/from the propeller hub to move the blades
Pros and cons of constant speed props
Pros: less wear, more efficient, increased performance
Cons: maintenance, cost, complexity
What MP/RPM settings should you avoid?
Hi MP and low RPM
Describe the fuel system on the duchess (tanks, sumps, fuel types)
2 50gal tanks with 103 total capacity. 1.5 unusable per tank
100LL (blue) and 100 (green) only
8 sumps total
Describe the fuel pumps on the duchess
2 engine driven, 2 auxiliary, 1 combustion heater
Describe the fuel crossfeed system and when/how to use it
Level flight, emergency conditions only
System cannot transfer fuel from one wing to another, instead each engine can draw from opposite side
operative engine aux pump ON
inop fuel selector OFF
operative fuel selector CROSSFEED
operative fuel selector ON/OFF as required
Describe the fuel selector valve
Each engine has one. Each valve also has a strainer and drain.
Positions: ON, CROSSFEED, OFF
3 hoses connect at the valve: In from tank & crossfeed (opposite tank), out to engine
Priming goes to which cylinders?
1,2,4
What’s your approximate fuel flow in the duchess?
23” 2300 RPM - 9 GPH
25” 2500 RPM - 11 GPH
Maximum slip duration
30 seconds
Minimum fuel level for takeoff
9 gal (yellow arc) per tank
Describe the electrical buses. Which are high load items for the battery?
Battery, Bus1, Bus2
High Load Items: Gear, flaps, landing lights, transponder, Nav-Coms
What voltage protection does the duchess have? (5)
Over-voltage protection – over-voltage relay & warning light, voltage regulator
Undervoltage/Alternator out – warning light
Emergency Precautions – Isolation breakers, temp controlled bus tie (ME 103 and After)
Starter-Engaged Warning Light (3733D only)
Describe the battery
Each side has two 12V batteries in a series or one 24V 55A battery (vented)
Describe the alternators
Two 28V 55A engine-driven alternators (belt-driven)
Alternators produce more voltage to compensate for loss in system.
Alternators are self-exciting at 1200-1400 RPM/50% load
Describe the heater, risks, protection and fuel burn.
45,000 btu Janitrol Combustion heater: Little furnace in the nose that is burning gas.
Same CO risk as carb heat.
Protected w overheat sensors that blows circuit breaker in nosewheel/nose baggage compartment at 300deg F. Must be reset by mechanic.
Burns 2/3 gal/hour from right tank
Operation for combustion heater
Ground: Blower on first, then heater on (blower stops with gear retract)
In-flight: Must have fresh air inlet set at least 1/2 open, monitor temp by heater pull knob
Shutdown: have blower on for 2 minutes
What moves the elevators, rudder, aileron, trim and flaps?
Elevators - cables and pulleys
Rudder - cables and pulleys, push/pull rods (steering)
Aileron - cables and pulleys, push/pull rods
Trim - cables & bungees
Flaps - electric motor under copilot’s seat
Placeholder card for control surface movements from TCDS (BE-76 System and Limitations page 7)
wing flaps down 35 +/- 1 aileron up 20 down 15 rudder right/left 30 elevator up 20 down 15 rudder tab right/left 20 elevator tab (w elevator neutral) up 4 down 20
Trim tab types
Trim tab deflects to relieve pressure
Balance tab – connected to yoke. The yoke moves it to move the elevator
Antiservo – yoke moves it to move the stabilator
Antiservo tabs – leads in the direction of the control surface
Moves more quickly than the manual control surface
https://www.boldmethod.com/learn-to-fly/systems/4-types-of-trim-tabs/
What static sources does the Duchess have?
One static port on each side of the aft fuselage
Alternate Static source on pilot side cabin wall, above landing gear extension tool.
Describe the vacuum system
One pressure pump on each engine interconnected to form a single system
Powers Attitude Indicator and Heading Indicator
Check Valve allows for continued operation with one pump inoperative
Normal Operating Range (Green Arc) – 4.3 – 5.9 inHg
2 red buttons for failure indication
What are the Service Ceiling altitudes for the duchess?
Twin Engine: 19,600 @ 3900lbs
Single-Engine: 6,200 @ 3900lbs
Single-Engine: 10,300 @ 3400lbs
Maximum Ramp Weight Maximum Takeoff Weight Maximum Landing Weight Maximum Zero Fuel Weight Useful load Standard Empty Weight Baggage Compartment
Maximum Ramp Weight: 3916 lbs. Maximum Takeoff Weight: 3900 lbs. Maximum Landing Weight: 3900 lbs. Maximum Zero Fuel Weight: 3500 lbs. (plane, people, baggage, and no fuel) Useful load 1470 Standard Empty Weight: 2446 lbs. Baggage Compartment: 200 lbs.
Flight Load Factor Limits
Flaps up: +3.8g / -1.52 Gs
Flaps down: +2.0 Gs
What MP reading should you expect to see at full throttle on takeoff?
About 1” below ambient (whatever you were reading before you started the engine). If it’s less, abort takeoff.
What does the MP read if the engine is inoperative and feathered?
Ambient or up to an inch less due to restrictions in induction system
Does MP indicate power?
No. It indicates how much fuel/air mixture is available to the engine and how much suction is being produced. At a given MP, increasing RPM will lower MP and vice versa?
Max Demonstrated Crosswind
25kts
Placeholder for questions to ask CFI:
Can a single alternators charge the batteries?
How can you tell if one of the 2 vacuum pumps has failed?
???
Where is the manifold pressure reading taken?
In the intake manifold, after the throttle and then venturi, but before the intake valve to the cylinder.
How does an unfeathering accumulator work?
High oil pressure from the governor charges the accumulator just moments after engine rotation begins. This gives you a single shot to unfeather.
