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What is the wing span of the Twin Otter?

65 Feet.


What is the length of the Twin Otter with the Short Nose?

49.6 feet


Where is the Datum located in the Short Nose Variant?

Approximately 6 inches forward of the nose cone fairing.


Where is the Datum located in the Long Nose variant?

Approximately 21 inches aft of the tip of the nose cone fairing


How many Caution lights are located in the Caution Light Panel?

18 Lights (9 per side)


How many Micro Switches are used with the Door Warning Light System?

4 Micro Switches.


Which doors are equipped with Doors Unlocked Micro Switches.

Long Nose Baggage, Aft. Baggage, Right and Left main exit doors
(or air-stair door)


What is the maximum positive “G “loading of the 300 Series?

3.17 Positive.


What is the maximum positive “G“ loading for a 100/200 Twin Otter?

3.21. Positive.


What is the maximum landing weight for the 300 series Otter on floats.

12500 lbs.


What is the maximum negative “G” loading for the 300 Series Otter?

1.5 Negative.


What category of flight operations is the Twin Otter Certified to operate in?

The Normal Category .


Is the Twin Otter capable of doing steep turns of 80 degrees of bank angle?

Perhaps it is, but the Maximum Legal Bank angle is 60 degrees.


Name three major differences on the Three Hundred Series.

Additional Vortex Generators on the Vertical fin, An increase in Allowable
Gross weight, Lowered Positive “G” loading, higher horsepower.


Why is there a Torque Limitation on the -27 powered 100 & 200 Series?

The possibility of the loss of rudder control at maximum power
during single engine operations at low airspeeds.


What is the VMO for the 300 series Otter on floats?

158 Kts. for Wipline Floats. (156 KIAS S.L. wheels)


What is VMC for the 300 series Otter on Floats.

67 Kts. 20 flap. 70 Kts. 10 flap Prop Feathered
64 KIAS wheels.


What is the VP/VB. speed for the Otter on Floats?

135 Kts.


What is VX. For the 300 Otter on Floats?

82 Kts. 87 KIAS wheels.


What is VY for the 300 Otter on Floats?

90 Kts. (wheels 100 Kts).


What is VY. 100 Otter on Floats?

90 Kts (wheels 100 Kts.


What is VFE Flaps 10 300 Otter Floats?

102 Kts. (100 KIAS wheels)


What does the abbreviation VXSE. Stand for?

Velocity Angle Single Engine.


What does the abbreviation VP/VB. stand for?

Velocity Manoeuvring Speed (full and abrupt control deflection).


What does the abbreviation VNE. stand for?

Velocity Never Exceed.


W hat does the abbreviation VYSE stand for?

Velocity Rate Single Engine.


Why is the VP/VB. speed lower than the VNE speed?

To prevent possible structural damage to the aircraft,
when full and abrupt movement of the flight controls are
used, and also to help prevent inadvertent high speed
stall, if encountering gusty wind conditions..


Are the Chip Detector Lights always included with the Caution light Panel?

No, they are an option and sometimes located in front of the co-pilot.


What is the maximum bank angle for normal category.

60 degrees


What could cause the Prop Reset light to illuminate?

Prop. Levers below 91% and or power levers below 75% N.G.


How many RED LIGHTS are located on the Caution Light panel?

There are no RED LIGHTS on the Caution Light panel.


What is your action for any Caution Light Illumination?

Call for the applicable QRH.


If the Aircraft has a Hydraulic Press. Fail light, is it part of the Caution Light System?

No, it is an add-on feature.


You have a failed generator and the buss tie is open, will all the Caution lights work?

No, several Caution Lights are powered from the Opposite Buss.


What Component controls the operation of the hydraulic system?

The pressure switch controls the pump operation.


Does the pressure switch have any effect on the standby hand pump?

No, it has no effect on hand pump operation.


Why is it important to shut off the electric pump if a system leakage is suspected?

To preserve as much fluid as possible for the hand pump operation.


If using the hand pump, is it necessary to pump full system pressure to
operate the flaps?

No, and if a leak is suspected, this would lead to further and more rapid
loss of the remaining fluid.


How much fluid does the hydraulic reservoir contain?

Approximately 2/3 of a U.S. gallon.(just over 2 liters).


What type of hydraulic fluid is used in the system?

Mil. H 5606 (Red in color).


Would any type of fluid work in the Hydraulic System?

Actually ,yes, but other types of fluid would contaminate the system, requiring
Maintenance to do extensive cleaning and component changes.


Could the Hydraulic Fluid tank be accessed in flight, in an emergency situation?

Yes, by lifting the flooring up in the cockpit.


Could the fluid level be checked in flight? And if so by what means?

On some aircraft only. (Dipstick.)


What is the other method used to check fluid level on the ground?

Some aircraft use a sight gauge on the fluid reservoir.


If Hydraulic Fluid were available to the crew, would it be possible to add fluid
In fight to the reservoir?



What precaution would have to be taken prior to adding fluid?

Electric pump would need to be turned off, and left off.


What occasion could arise, that Fluid might need to be added in flight?

A choice of a flapless landing on CAP floats, or adding fluid.


Normal operating hydraulic pressure limits on both pre and post mod aircraft?

Approx. 1250 psi. to approx. 1600 psi.


What would be an appropriate action if the Hydraulic System
was noticed to cycling fairly frequently?

Turn off the electric pump.


Which Buss does the hydraulic pump get the power from?

Left hand D.C. Buss.


Which Buss does the hydraulic pump fail light get it’s power from?

Left hand D.C. Buss.


The hydraulic pump circuit breaker has popped in flight is it considered ok to reset it?

No , because the pump may have seized up.


If the flap selector was set to approx 20 degrees, and the flap position indicator
was indicating some other number, would pumping the hand pump result in
any pressure building up on the pressure gauge?

No, there can be no pressure built up until the selector valve and the actual
Flap setting agree.


Is this possible scenario a problem?

(If the flap selector was set to approx 20 degrees, and the flap position indicator
was indicating some other number, would pumping the hand pump result in
any pressure building up on the pressure gauge?)

Not at all. The pressure will start to build when the flap position equal’s the
flap selection. (Provided there is fluid in the system.)


What are the two pressure limits for the two different system pressure relief

1750 PSI. and 1950 PSI.


What are the two types of brakes that might be installed on a Twin Otter?

Goodyear and Cleveland.


What is the difference between the two types? (of brakes)

The Goodyear brake disc is the floating type, and the Cleveland is
solidly mounted to the wheel assembly.


How is the shock of landing handled on the Twin Otter?

By using two urethane compression blocks, on each main gear and an air
over oil, oleo on the nose, and to some extent, Air pressure in the tires.


Considering the main gear is hinged to the aircraft with two bolts, fore and
aft, what prevents the gear from folding under the aircraft in flight?

The platen center bolt that retains the urethane blocks in place.


What is the tire pressure for the main wheels summer and winter?

38 And 34 PSI of Nitrogen.


What is the normal extension of the Nose oleo?

Approximately 6 to 8 inches.


The Nose gear is steerable how many degrees either side?

60 degrees left or right.


What station of the aircraft is the Nose gear attached too?

Station 60 (forward cockpit bulkhead.)


What is the normal inflation pressure of the Nose Wheel tire?

32 PSI of nitrogen.


How is the Nose Wheel Steering actuated?

Cable and pulleys from the lever in the cockpit.


What provides the motive force for the Nose Wheel Steering?

Pressure from the Aircraft Hydraulic System.


Does the Steering draw pressure from the Brake or the main Accumulator system?

The main Accumulator System.


If the hydraulic system were to start leaking in the brake system could all
Hydraulic pressure be lost?



If the leak were only in the Flap/Steering side would all pressure be lost?

No, the Brake system will hold pressure.


Name 4 systems that use aircraft hydraulic pressure to operate?

Brakes, Flaps, Steering, and Ski’s if installed.


Is it possible to operate all hydraulic systems if the electric pump fails?

Yes . Use the manual hand pump.


Is it necessary to pump up full system pressure by hand in order to operate
the various systems ( IE. 1300 /1600 PSI.)?

No, flap and steering systems can selected and pumped as required.


If hydraulic pressure is reading zero and the flaps are selected down on the ground,
will the flaps extend?

Yes, the weight of the flaps will cause them to fully extend.


If direct pumping flaps down in flight, what indication might you see on the gauge?

Pressure fluctuating between 0 and 750 psi until the flaps are at the selected value.


What systems of the aircraft does bleed air operate?

Environmental, de-ice boots, intake deflectors, and autopilot.


What pressure is the bleed air regulated to for the operation of the de-ice boots?

18 PSI.


What is the maximum pressure allowed for the bleed air system?

25 PSI.


What is the time for a complete boot cycle in auto-fast -mode?

1 minute (5-5-3-3 ) 44 seconds off.


What is the time for a complete cycle in auto-slow-mode?

3 minutes 5-5-3-3, then 164 seconds off


If equipped , what do the two blue lights for the tail boots indicate when illuminated?

Only that pressure is available for boot inflation.


Illumination of the pneumatic low pressure light indicates what?

That there is not enough pressure available to inflate the boots.


What is needed for the operation of the optional propeller boots.

Electrical power and oil pressure above 40 PSI.


The Flaps installed on the Otter are called what type?

Full Span Double Slotted Fowler Flaps.


Name the individual Flaps on the Otter.

Inner Fore Flap, Outer Fore Flap and Inner Trailing Flap.


What does a Servo Tab actually do?

It deflects in the Opposite Direction of the Control Surface Movement
to Lessen the Forces Required by the Pilot to move the Control.


What does a Trim Tab actually do?

It is set to a Required Deflection to Remove Control Pressure.


What is the purpose of the Flap-Elevator Inter-Connect Tab?

To Lessen the Pitch-up Moment of the Aircraft when Flaps are Extended.


Which Elevator has the Trim Tab attached?

The Left Hand Elevator.


Which Tab is located on the Upper Portion of the Rudder?

The Rudder Trim Tab.


Which Tab is located on the Right Elevator Assembly?

The Flap Elevator Interconnect Tab.


How many Servo tabs are installed on the Otter.

Three Servo Tabs.


Where are the Servo Tabs located?

Inboard end of each Aileron and the Bottom of the Rudder.


How many Stall Bars need to be installed on the Otter if floats are installed?

Three Stall Bars, one on the Left Wing and two on the Right Wing


What type of mechanism is used to Transmit Control inputs to the Flight
Control Surfaces in the Otter?

Cable and Pulleys.


What method is used transmit Trim Inputs to the Elevator and Rudder.

Cable ,Drum, and Screw-Jacks.


How is the Aileron Trim Actuated?

An Electric Motor installed inside the Left Aileron.


Are the Ailerons attached to the wing?

No, they are attached to the Outboard Fore-Flap.


Are the Inboard Trailing Flaps attached to the Wing?

No, they are attached to the Inboard Fore- Flap.


What type of linkage connects the Flap Control Handle to the Flap Actuator?

Cable, Drum and Pulley.


What type of linkage from the Flap Actuator to the Flaps?

Push –Pull Rods and Bell-Crank Assemblies.


What is the purpose of the Flap/ Stall Vane Micro-Switch?

To delay the actuation of the Upper Stall Vane
until greater than 12 degrees of flap are extended


How many Screw jacks are located in the Flap Elevator interconnect system?

Two, one at each end connected by cable and drum assemblies.


Is the flap Elevator Interconnect more or less effective after 10 flap has been selected?

More effective after 10 degrees .


Do the Flap Rods Pull or Push to lower the Flaps?

The Flap Rods Pull to Lower the Flaps.


How is the Flap Indicator on the windshield pillar actuated?

Cable from the actuator pulls the indicator bar downwards.


Are the Markings near the Flap Selector handle accurate?



How many Inverter Relays are installed in the 310 series?

None are installed ,as both L. & R. Inverters operate simultaneously.


Which D.C. Buss does the Right Inverter get it’s power from?

The Right D.C. Buss


The Right Generator is offline, and BUSS TIE SWITCH is open,
will the Right Inverter operate?

No, as there is no source of D.C. Power for the Right Inverter.


The Left 400 Cycle has illuminated, your action is?

Check list for 400 Cycle Light.


You turn off the Left Inverter and the 400 Cycle Light goes out, your action

Your action should be to leave the Inverter Switch OFF, as this
indicates a Buss Failure. (CHECK LIST)


List the types and voltage of the power output from the Inverters?

400 Cycle, both 115 and 26 Volt A.C.


You turn on the Master Switch prior to start. A 400 Cycle Light
Is illuminated. A possible cause might be?

An Inverter has failed or a Failure of a BUSS.


What is the purpose of the Inverter Relay?

To Energise either the #1 Inverter or the #2 Inverter


Which D.C. Buss does the #1 Inverter get it’s power from?

The Left D.C. Buss only.


Which D.C. Buss does the #2 Inverter get it’s power from?

The Right D.C. Buss only.


The #1 inverter and the Right generator have failed, and the Buss
Tie Switch is open, can you get A.C. Power back?

Yes , Close the Buss Tie Switch and select #2 Inverter.


How many positions are there on the Inverter Switch?

Two positions , #1. and #2


The #1 Inverter fails and you cannot get #2 inverter on line.
The most likely cause is?

Failed Inverter Relay.


#2 Inverter has failed in flight .You cannot get #1 Inverter on line.
Name two possible causes.

#1 inverter is also unserviceable or the Inverter relay
has failed.


How many Cells are there in each Fuel Tank Group?

There are Four Cells in each Tank Group.


How many Boost Pumps are located in each Fuel Tank Group?

There are two Boost pumps located in each Fuel Tank.


What is the normal Fuel Pressure provided by the Main Fuel tank Boost pumps?

Approximately 22 PSI.


At what Pressure might the Boost Pump Fail Light illuminate?

At Pressure’s lower than 2 to 3 PSI.


The book say’s that each pump will produce approx. 450 LBS. of Fuel per hour.
Explain how one pump will keep both engines running at max power?

A serviceable pump will produce 450 LBS. per hour against a head of 22 PSI.
If only one pump is providing fuel for both engines, the head of pressure is
reduced to almost zero, allowing the pump to provide a greater volume of
fuel. (approx 950 lbs per hour, The Fuel pressure will be greatly reduced)


How are the Boost Pumps cooled?

They are Cooled and Lubricated by Fuel only.


What might be a possible result of failing to pull the circuit breaker on a failed
Boost pump as per the emergency check list for a failed pump?

It is theoretically possible to overheat a seized pump resulting in a fuel tank fire.


What is the normal pressure for the optional wing tank Boost pumps?

Normally 23 to 24 PSI.


Why is this pressure higher than the main tank pumps? (wing tanks)

To ensure that fuel is used from the wing tanks when they are selected.
(The pump that has the higher pressure will deliver the fuel to the engine).


What is supposed to ensure that the wing tanks are not overfilled,
when refuelling them from the belly tanks?

The Fuel Level Control Valve Located in each wing tank.


Why may we not transfer Fuel to the wing tanks in flight?

The possibility of the Fuel Level Control Valve failing and allowing Fuel to be
transferred overboard unnoticed by the flight crew.


Why are the main boost pumps left “on” when using fuel from the wing tanks?

To prevent the possibility of a Low Fuel Pressure flame-out when the wing
tanks are emptied.


What material are the Fuel Tank Cells constructed from?

Rubberized Nylon.


How many Fuel Cells are there in the total Main Fuel Tank group?

There are Eight Fuel Cells in the Main Tank Group.


What are the Cell numbers of the two Collector Cells?

Cell numbers Four and Five.


Which Cell numbers have the filler necks installed?

Cell numbers One and Seven.


Which two Cells have no flapper valve installed in the bottom?

Cell numbers One and Seven.


Why are there no flapper valves in these two Cells?

To facilitate rapid refuelling of the aircraft.


Why do the Collector Cell Flapper Valves, not have a hole in them?

To prevent the rapid return of the Fuel to the other Cells. the Collector Cell
Must remain nearly full to help prevent fuel starvation in normal flight.


How does Fuel move from the Filler Cell to the other Cells when fuelling?

Via the interconnecting Fuel Manifold Plumbing.


How many fuel vent outlets are installed in the airframe?

There are two vent outlets, one under each wing, outboard of the strut.


How many vents are located in each fuel cell?

There two vents in each cell, one on each side.


Is there a fuel return line to the tanks from the engine?

Fuel in excess of engine requirements is returned to the aft tank only.


What might be the result of a plugged or iced over fuel vent?

It could lead to a collapsed Fuel Cell.


How are the Fuel Vents protected from icing over?

By using a shaped block in the airflow in front of the vent.


The tunnel shaped covering over the vent outlet provides what additional purpose?

It provides a slight positive pressure to ensure against Fuel Cells collapsing
as fuel is used by the engines. Also provides lightning strike protection.


Normally, a low fuel light would indicate how many lbs of fuel remaining?

75 lbs. in the forward tank and or 110 Lbs. remaining in the aft tank.


What might be another problem that could be indicated by a low level light?

It might be a failed Fuel Transfer pump.(ejector pump clogged)


How would you verify this problem? (failed fuel transfer pump/ejector pump clogged)

By checking the Fuel Level remaining on the gauge, re the opposite gauge and
the time the engines have been running.


You have been transferred to a second or 32nd airplane during the day.
You note 250 lbs, of fuel per tank remaining. You fuel up for the trip ,
After 20 minutes of flight you note the fuel level is dropping in one tank much faster
Than the other tank. Is there a potential problem and if so, what might it be?

Yes, the Cross Feed valve may be failed in the open position.


How would you handle this scenario realistically? (Cross feed valve failed in open position)

You might use the cross feed valve to select the fuller tank
periodically, to keep the fuel balanced.
The pump that has the higher pressure will provide the fuel.
The selector knob via the auto change over system will turn off
the non desired pumps as long as cross Feed is selected.
And the #2 standby pump is not selected on!


What force drives the propeller to the feather position?

Springs and counter weights.


How many governors are installed on the Twin Otter Propeller system?

Three.(Constant speed, Over-speed, and Fuel Topping governor.)


What is the maximum governing speed of the CSU?



What is the limiting RPM of the over-speed governor?

101.5 %


What is the limiting speed of the Fuel Topping governor?

102 %


How do the CSU and the Over-speed governor control prop RPM?

By Restricting or Dumping oil pressure (flow)


How does the Fuel Topping governor differ in operation from the other

The Fuel Topping Governor restricts fuel only to prevent over-speeds.


Which governor controls maximum prop RPM in the reverse range of

The Fuel Topping Governor


What “controls” the flow of oil to the propeller in the Beta-Reverse range ?

The Beta Reverse Valve.(actuated by the power lever in the reverse range.)


At what speed is the propeller limited too in the reverse range?

91 % (+ or – 1 %)


If the prop RPM were to exceed this limit what should happen? (max propeller speed in reverse range, 91%)

The Fuel Topping governor should begin to restrict fuel to the engine.


How does it do this? (fuel topping governor restricting fuel)

By bleeding off “PY” reference air and restricting fuel to the engine .


What purpose does the “Reset Arm” serve in relation to Reverse Beta operation?

It lowers the Datum of the Fuel Topping governor from 102% to 91 %


If the CSU. were to fail at Max. Power which governor would limit the RPM,
and at what RPM?

The Over-speed Governor should function first at 101.5 %


Is the Over-speed Governor functional in the Beta reverse range?

Yes, it is functional, but would not normally actuate because
The Fuel Topping Governor should restrict the RPM to 91 % only.


What is the diameter of the Twin Otter propeller?.

8 feet 6 inches in diameter


The standard Propeller on the Twin Otter is a Hartzell 3 bladed reversing
and full feathering Propeller. Are other types of Propellers approved?

Yes, McCauley makes a four bladed prop for the Twin Otter.


If engine oil pressure were lost, what effect would this have on the propeller?

The Propeller would go to feather.


Is 80 to 100 PSI. IE, Engine only Oil Pressure, enough to control the Propeller?

No, the CSU boosts Engine oil pressure to approx 300/400 PSI.


Is the Beta Valve normally open or normally closed during operation
in the constant speed range?

The Beta valve is normally fully open in the constant speed range.


The Engines have been shut down on the Latches, where should
the Prop Levers be positioned for Start-up?


The Full Feathered position in the Maldives due to the temperature and altitude.

So that the engine receives only Min. Flow Fuel for the start, resulting
in cooler engine starts.


You are in cruise at 76 % prop RPM. You notice the following.
Props out of sync, torque decreasing, and Ng speed decreasing.
What has likely happened?

The CSU likely has a fault and the Fuel topping governor is controlling
the engine RPM to prevent an over-speed. (approx.6% above prop setting)


You are at maximum power for take-off and the CSU fails,
what will the Rpm. Indication be on the Np?

You would likely see 101.5 %.


Which governor is controlling the RPM? (if CSU is failed)

The Over-speed Governor is controlling the speed of the prop.


If both the CSU and the Over-speed governor were to fail, at max. power
what would be the indications in the cockpit?

102 % Np, and decreasing Ng, as the Fuel Topping governor starts
restricting fuel to control the over-speed.


At what N.P. Does the auto feather normally arm?

86/ 88 % NP


Which arming relay provides power from the Buss, to the left time delay switch
In order to actuate the auto feather sequence of the left engine?

The Right Arming Relay.


What function does the test switch perform regarding the power lever
switches, when performing the auto feather test sequence?

The Test Switch bypasses the Power Lever micro switches.


Are the power lever switches wired in series, or in parallel, for the auto
feather system?

They are wired in Series.


What position do the power levers have to be at in order to Arm,
the Auto Feather system?

They must both be at or above 86/88 % NP.


During an X wind take off, auto feather on, the left power lever is at 50 PSI,
and the right power lever is at approx. 40 PSI. Will the auto feather be armed?

Yes, as the Np. would be at or above 86/88 % on both


What does the abbreviation PT6 A-27 stand for?

PT. stands for Propeller Turbine, 6 stands for engine family,
A stands for two stage gearbox, and -27 stands for engine series.


What does the term Free Turbine mean?

There is no mechanical coupling between the gas generator section and the
power section.


Which is the critical engine on the Twin Otter?

The Left Engine.


In reference to Twin Otter Limitations, what does the capital letter “P” always mean?

The capital P always stands for pressure.


What does the capital letter “N” always stand for?

Rotational speed.


What does the small letter “p” stand for?



In reference to the Twin Otter, what does SHP stand for, and what location?

Shaft horse power at the propeller hub.


Describe ESHP. In reference to the Twin Otter.

Shaft horse power at the prop hub plus thrust from the exhaust stacks.


How many stages of compression are there in the PT6-27 Engine?

There are four stages , three Axial and one Centrifugal.


What is the speed of the compressor assembly at 100%?

37,500 rpm at 100%.


What is the speed of the power turbine at 100%.

Approximately 33,000 rpm at 100%.


How many fuel manifolds are installed on the PT6 -27 engine?

There are Two Fuel Manifolds.


How many fuel nozzles are installed on the -27 engine?

There are 14 fuel nozzles installed.


How many fuel nozzles are providing fuel initially when fuel lever is first turned on?

10 nozzles only.


How and when do you activate the other 4 fuel nozzles? (besides the first 10)

You do not activate them, they come on automatically at 32 to 36 % NG.
they are activated by increased fuel pressure due to increased RPM.


What are the reduction ratios in the two stage gear box?

3 to 1 and 5 to 1 for a total reduction of 15 to 1.


How many fire detection probes are installed in each engine nacelle?

There are four in each nacelle.


What is the activation temperature of the forward post mod. Probes?

The post mod probes activate at 450 degrees C.


What temperature will activate the rear temp probes?

The rear probes activate at 300 degrees C.


How many probes need to be activate in order to get a fire warning?

Any “ONE” probe will activate the fire warning system.


On your walk-around you notice the yellow burst disc is missing from the engine,
this would indicate what?

It would most likely indicate an intentional discharge.


This has happened on your morning inspection at a resort,
can you fly the airplane home? (Intentional discharge of fire bottle)

You would first have to check the MEL.


What is the engine fire bottle filled with?

Freon 13 B 1


What conditions have to be met in order to actually activate the engine fire bottle?

Pull the handle, but, the Master Switch has to be on.


What oil temperature is recommended for fuel heat to function at take off?

55 degrees C.


What is the time limit for operation in the reverse range?

1 minute.


Why is this limit in effect? (maximum time in reverse)

Possible heat damage to the cowling and wing leading edge.


How long may the generator reset switch be held in the reset position?

Not longer than 2 seconds.


What reduction must be applied to the NG is operating below -30 C.?

2.2 % NG for each 10 degrees C. Below -30 C.


Name the three things that happen when the fuel control lever is turned on?

Fuel is fed to the fuel nozzles, the manifold drain is closed, and the
starter Is switched to series for increased starter speed.


Why is it important to pause in the on position momentarily before resetting
the generator?

To ascertain the generator did not reset itself.


What is the difference between an MMEL and an MEL?

MMEL from the aircraft manufacturer, ATA. and the Aviation Authority,
And an MEL is made by the Operator and the Aviation Authority.


What is the purpose of the MEL?

To allow for continued service with some defects while maintaining
An adequate level of safety.


I f an item on the MEL has a category letter “B” this means what?

The item may be deferred for a maximum of three days.


The symbol M# is placed next to an item on the MEL. This means what?

Maintenance personnel required to defer the item.


Th e symbol “O” is placed next to an item on the MEL, this means what?

The item has an effect, or restriction on the operation of the
aircraft that the pilot must comply with either before or during
operation of the aircraft.


The word “Category” as from the MEL means what?

The Repair Interval allowed


How many “Categories” are there in the Twin Otter MEL?



Name them ? (MEL categories)

“A” Must be repaired as per the remarks column
“B” Three days
“ C” Ten days.
“D” One Hundred and Twenty days


What are the 6 steps the pilot must follow in the deferral of an item?

1. Check the MEL first,
2. Enter the item in the journey log book
3. Defer the item in the log book.
4. Enter the item in the deferred log.
5. Fill in and place the placard sticker.
6. Advise MTX.


What has to be written on the in-operative sticker?

ATA chapter #, Item #, Category letter, Log Sheet #.


Where is the MEL located in our Twin Otters?.

Under the Captains seat.


Why are Flight Controls not listed in the MEL?

Because Flight Controls are obviously required.


A “Category “ B item has expired, may it be re-deferred?

No it may not be. The reason for the MEL is to allow
Operation for a limited time only for repairs , or getting parts.


An item has been legally deferred on an Aircraft, is the pilot now
forced to accept the aircraft for service?

No, he is not!!! The pilot must first assure himself that the
flight can be concluded with an acceptable level of safety.
Only then may the flight proceed!.


What is the actual horsepower rating of the – 27 engine, Std. Atmosphere at sea level?

680 shaft horsepower at Sea level.


What is meant by the term FLAT-RATED?

It means the power out-put of the engine is restricted by the manufacturer.


How much power can we legally pull from the -27 at sea level?

620 horsepower only.


Why should the power computer, or calculation be used before each take-off?

To verify the actual legal power setting that may be used.


What side benefit is realized by using the power computer before take-off?

The actual condition of the engine, or the amount it has deteriorated.


Why would this be a concern to the flight crew? (amount the engine has deeriorated)

Single engine performance will suffer with a deteriorated engine.


Above what altitude would a -27 produce less than 620 horsepower?

From the power graph, above 5500 feet the -27 starts to lose power.


After doing a power computation prior to take-off, we note that we had to pull back the
power on one engine to avoid over temping the engine. This means what?

The engine performance has deteriorated and must be investigated or rectified
Before further flight.


What Three Items are required to do a Power Computation?

A Graph or a Power Computer, the Temperature, and the Altitude.


What is the max power allowable for take-off @ISA at 4000 ft. Alt.

50 PSI: this is an engine limitation not to be exceeded in normal operation.


The same as above calculation, but using an index of four?

(What is the max power allowable for take-off @ISA at 4000 ft. Alt.)

46 PSI. Is the max allowable.


Calculate torque for take-off @ 12.000 ft. altitude @ISA. Temp?, Index of three?

38 PSI.


Using the balked landing graph, calculate rate of climb two engines at 12000 lbs.,
34 degrees at sea level?

Approx. 900 FPM.


Using the T/O to 50 ft. graph, calculate ( 34 degrees,11.500 lbs., 5 Kts. tail wind)
give the total distance to 50 Ft. altitude.?

Approx. 2350 Ft.


What would be max permissible T/O weight for ISA +20 at sea level? (300) Series,
In order to meet single engine climb criteria?

12.100 lbs


16. Using the X wind chart what effect does a wind 75 degrees off the nose and
blowing at 25 Kts. do for us?

About 24 Kts. X wind and about 7 Kts. for a helping hand.


Calculate maximum allowable torque for 8000 ft. And 20 degrees.

About 41.5 Psi @ 96% NP.