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DHC 8 oral study guide
Terms in this set (63)
What accessories are on the accessory gearbox
F Fuel Pump
O Oil Pump
D DC Gen
What accessories are on the Propeller reduction gearbox
H Hyd Pumps
A AC gens
What functions does the ECU provide?
Engine Uptrim 10%
Refines Fuel scheduling to the MFC
Prop underspeed protection
HBOV (handling bleed off valve).
What does the TOP position provide on the Q200?
Normal takeoff power (NTOP)
What drives the Prop to feather position?
Removing fine pitch oil from one side of a dual acting pitch change mechanism (piston)
When does the Autofeather arm?
Both power levers at takeoff position (some point forward), Both torques >38%
When does Autofeather activate?
Both power levers at Takeoff position
Good engine torque >38%
Failed engine torque <28%
What is the Autofeather sequence?
The SCU senses a failed engine, sends an uptrim signal to ECU to the operative engine.
After a 3 second delay, the Aux feather pump (DC pump) is activated, feathering the failed engine and opening the feather Solenoid valve.
The SCU (signal control unit) sends a signal to allow the failed engine to pass through the prohibited range and fully feather.
The Autofeather system disarms, preventing the good engine from feathering.
How does the Alternate Feather Switch work?
Operates the same Aux feather pump as the autofeather system, but utilizes a separate reservoir (1.7 qt.). May be operated with or without the engine running for a single feather or unfeather operation.
How does the prop feather using the condition lever (manual feather)?
Utilizes the PCU to open the Feather Solenoid Valve, dumping fine pitch oil and allowing the prop to feather.
How does the POG work?
The POG prevents prop overspeed in the air by dumping fine pitch oil if NP is exceeded.
On the ground the POG will bleed off P3 bleed air causing the fuel to the engine to decrease and thus slowing the prop.
What is the Prop Governor range?
In this range the prop is controlled by the PCU and produces forward thrust between 900 and 1200 RPM
What is the Prop Beta range?
This range starts just forward of flight idle and continues to max reverse. On the ground this range is controlled by the Power Levers (blade angle) and the ECU prop speed and underspeed control (above 780 prohibited range)
What is the Beta Lockout system?
Used to prevent/protect against inadvertent selection of power lever below flight idle during flight. At WOW and >20' AGL the system arms and if power levers are selected below flight idle will modulate fine pitch oil to the PCU to maintain 970-1030 prop rpm, ECU reverts to manual and igniters to continuous.
What is the Beta backup system?
Prevents a failure of the PCU from causing the props to enter the ground beta range in flight. During flight if prop angle is <16.5 degrees the beta backup will cycle the blade angle (coarsen pitch) to above 16.5 degrees and then turn off causing the Prop Ground Range Lights to cycle. Advancing the power levers above flight idle should solve the problem.
What are the main DC power sources?
2 NiCad batteries (24V 40 amp hour, 24V 15 amp hour)
2 DC Gens.
2 TRUs (115 volt variable to 28 Volt DC)
What are the main AC power sources?
2 AC gens
What happens when the Batt Master is turned on?
Connects the Main and Aux batteries to the right and left essential busses
What happens when the Aux Batt is turned on?
Connects the Aux Batt to the left Main DC bus with one way power only (to charge the Aux batt)
What happens when the Main Batt is turned on?
Connects the main battery to the right main DC bus.
What does the Bus tie switch do?
Closes the Main bus tie (connecting right and left main busses) for use in starting the #1 engine first, when the #2 DC gen is MEL'd.
Why do we wait to turn on the anti-ice until the condition levers are out of feather?
Anti-ice is AC driven. AC gens are not online until condition levers are out of feather. (except Pitot tubes and Static ports which are DC)
What happens if one TRU fails?
The secondary bus tie will close (horizontal) allowing the the opposite side TRU to power the secondary bus.
What happens if one DC Gen fails?
The Main bus tie closes powering the opposite side main bus from the remaining DC gen.
What happens if both DC Gens fail?
The Main Secondary bus ties close (vertical) allowing the Main busses to be powered by the TRUs.
What happens if both TRUs fail?
The Main Secondary but ties close allowing the secondary busses to be powered by the DC gens.
What happens if 2 DC gens fail and a TRU?
The secondary bus tie will close powering the failed secondary bus, but the main secondary bus ties will remain open and both Main busses will be unpowered.
What happens if 2 TRUs and a DC gen fails?
The main bus tie will close powering both main busses, but the main secondary busses will remain open leaving both secondary busses unpowered.
What do the Inverters do?
Convert 28V DC into 115V AC for frequency sensitive items.
What items are on the hot batt bus?
D Dome and boarding lights
E Emergency Fuel and Hyd shutoff valves
E Emergency lights controller
P PA emergency power
F Fire bottle squibs
What does the BBPU do?
The Bus Bar Protection Unit senses an electrical failure and will inhibit the closure of the main bus tie for 10 seconds. If the system senses a failure it will isolate the failed battery and DC generator.
How can we recognize a left from a right DC bus failure?
Left failure -DC BUS, #1 DC GEN, AUX BATTERY, AUX INV lgts.
Right failure-DC BUS, #2 DC GEN, MAIN BATTERY lgts.
What happens when an AC Gen fails?
AC gen cross tie will close no system losses.
What happens with a dual AC Gen failure?
All 115V AC services lost, main secondary ties will close (vertical) to allow the DC gens to power the secondary busses which would have been lost due to TRU failure.
What type and power engines does the DHC 8 have?
P&W 123 and 123D 1950-2140 and 2150-2380 Hp (200/300 respectively).
How many hydraulic systems are there?
3 systems including the handpump.
What items are one the Hydraulic #1 system
I inboard spoilers
BBrakes (main wheel)
A anti skid
R Rudder (lower)
What items are on the # 2 Hydraulic system?
L landing gear
O outboard spoilers
S nose steering
E Emer brake
R Rudder (upper)
What does the #2 Eng Hyd pump caution mean?
#2 Hyd pump failure
Where are the #1 and #2 Standby (SPU) hyd pumps located?
#1 - in the aft section of the #1 Nacelle, #2 in the rear fuselage equipment bay.
Why is the #2 SPU located in the rear equipment bay?
for use by the ARPS system.
What is the primary function of the PTU?
To assist in retracting the landing gear in case of #2 Engine failure on takeoff.
When will the PTU operate automatically?
When it senses loss of #2 hyd pressure and the Gear is selected Up.
If an engine fails on takeoff what hydraulic systems are inoperative?
None. The standby pumps will operate (AC driven).
What are the 18 PSI consumers?
B Bleed system for airconditioning and pressurization
A main door accumulator
R Rudder shutoff valve
N Nacelle purge drains
O Normal outflow valve (suction for torque motor)
P Pressure regulator valve.
What are the sources of bleed air?
HP and LP bleed sources. On the ground HP bleed is used up to 65 PSI controlled by the #1 pressure switch. above 65 PSI a pressure switch will shutoff HP bleed. In flight the #2 pressure switch controls bleed up to 55 PSI unless ice protection is selected on (boots), then the #1 switch takes over.
What happens with a #1 or #2 Bleed Hot caution light?
The respective system will automatically shutdown the bleed by closing the HP shutoff and Nacelle shut off valves until the condition is remedied.
What is the function of the HBOV?
prevents compressor surges and stalls and allows LP bleed to flow through the precooler.
What is the difference between auto and man modes of airconditioning?
Manual is operated by us and does not provide automatic overheat protection.
What is the difference between Air Cond Pack Hot on the 200 and either Cabin Pack or FLT Compt Pack Hot on the 300?
On the 200 with AIR COND PACK HOT, the HP and Nacelle shutoff with close bleed to the ACM ultimately causing depressurization. On the 300 the Bleed is shutoff using the PRSOVs which will only shutdown a single PACK and not cause depressurization.
How is the cabin ventilated if the PACKs fail?
Through use of the RAM air scoop on the sides of the dorsal fins. A valve opens when the PACK, PACKs fail that allows air into the cabin. The Safety outflow valve should also be opened.
What are the different anti-ice/de-ice systems?
Wing/tail/nacelle lip boots. Prop heaters (AC), engine intake heaters (AC), elevator horn heater (AC) Pitot and static ports (DC), windshield heat (AC).
What is the time for the boots on fast or slow?
Fast = 240 second cycle, 6 seconds per boot + 204 seconds dwell
Slow = 60 second cycle, 6 seconds per boot + 24 second dwell.
What is the difference between above -10 and below -10 on the prop heater?
Above = 10 seconds per prop pair of heating
Below = 20 seconds per prop pair of heating
both have a 60 second cool down period.
Will the Prop heat come on on the ground?
No WOW switch.
How are the stall transducers powered (200)?
DC on the ground and AC in flight.
What are the powered flight control surfaces (HYD)?
Rudder, Spoilers, Flaps.
What angle deflection does the rudder use?
12 degrees with the flaps at 0, 16 left and 18 right with the flaps out of 0.
What pressure is regulated to the rudders?
1500 PSI below 140kts, 150 kts (300), 900 PSI above 140 or 150 kts.
What items cause the Takeoff Warning horn to sound?
Flaps less than 5 or greater than 15, Condition levers not max, trim out of middle, ECU selector not at TOP.
What causes the landing gear warning horn to go off?
a)Gear not down, Flaps 15 or greater, autofeather system not on, power levers below takeoff setting.
b)Landing gear not down and locked, one or both power levers at or near Flight Idle and airspeed below 130 kts.
What are the Start Abort Criteria?
No lightoff within 10 secs
no oil pressure by starter cutout
ITT limits exceeded or approached
Engine fails to accelerate.
What is the memory item for Engine start abort?
Condition lever-Fuel Off
engine start abort checklist.
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