Bell 47 Pilot Notes

TC's B47 Tips

Click here: B47 Preflight checklist

Click here: Startup Procedure - Turbocharged engine

Emergencies: 

For the best outcomes in an emergency situation, A  PILOT MUST CONSTANTLY MENTALLY RUN THROUGH THE EMERGENCY PROCEDURES DURING NORMAL OPERATIONS.

Many emergency actions should not be practiced unless with a type qualified pilot/instructor and in a helicopter with dual controls.  

CONSIDERATION SHOULD BE GIVEN TO THE PRACTICALITY OF  MAYDAY/PAN CALL OR EVEN, IF TIME PERMITS - AND IT DOES IN SOME  EMERGENCIES - USING THE RADIO TO ASK A MORE EXPERIENCED PILOT  FOR ADVICE.

REMEMBER, IT IS TOO LATE WHEN THE EMERGENCY OCCURS TO START THINKING WHAT YOU SHOULD BE DOING.

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JAMMED COLLECTIVE

INDICATIONS:  THE COLLECTIVE WILL BE LOCKED SOLID

AIRMANSHIP:  MAYDAY-PAN-ASK FOR HELP/ADVICE

ACTIONS: Firstly check that the collective friction is off and nothing is obviously jamming the collective lever.  (Check the dual collective if fitted). 

If there is nothing obvious proceed as follows:  

Note the M.A.P. at which the collective is jammed.  Compare this with the power required to hover at your last takeoff.

If the power indicated is less than hover power proceed as follows...

Excess height can be overcome by diving the helicopter (watch your VNE) to about 200-300 feet AGL at a suitable landing area (about a 100 yard long clearing).

Set yourself on finals with the ambient wind preferably from the left front, the next best is straight ahead.  The worst is from the right front.

Wash off your IAS in a tight turn until about 15 Kts is attained roll out on to finals. 

An attitude/IAS of less than effective translational lift will be required next.

NOTE: THIS IS AN ATTITUDE/IAS  MANEUVER - NOT A RATE OF CLOSER MANEUVER. Hold the attitude/IAS to give a R.O.D. of not more than 300 ft per minute.  (To avoid vortex ring).

If it appears you are under shooting the landing area, a small (1/4 inch) change in attitude to increase the IAS will slow the R.O.D. and make the approach angle shallower. 

If you are overshooting a small decrease in IAS will steepen the angle but this will also increase the R.O.D. which - with the low IAS and medium power setting - will put you in the area of Vortex Ring.

In the case of over shooting decreasing the RPM with throttle will increase the R.O.D. and steepen the angle without reducing the IAS.  In practice the RPM can be reduced to as low as 2900 ERPM.  In the real situation it can be reduced lower but not lower than 2800 ERPM.

It may be safer, if you are overshooting, to carry out a descending orbit.

At about 20 ft. AGL there will be a strong instinctive pilot tendency to slow the helicopter to keep the closure rate constant. THIS IS WRONG!!!! Don't do it!!!

To overcome this tendency visualize the helicopter power curve and at 20 ft, push the cyclic in the direction the helicopter is traveling to make a small acceleration and therefore increase the IAS. This makes the helicopter more efficient and reduces the rate of descent.

At 3 ft AGL gently reduce the IAS and the helicopter will slowly sink onto the ground. (Again think of the power curve to see why this happens).

On the ground reduce the throttle, hold heading and when the helicopter has stopped switch off the engine.

If the collective has jammed at very high power which gives you OGE performance the following methods may be used to get the helicopter to descent...

1.  Reduce ERPM out of the green operating range down to 2800 ERPM

2.  Carb heat on. This richens the engine fuel/air mixture and reduces engine power

3.  Turn one magneto off (This is a last resort at below 10 Ft AGL - you don't want an engine failure with a jammed UP lever )

At low power the angle will be flatter with a higher IAS.

At high power the angle will be steep and IAS lower.

With a jammed collective the helicopter can be normally flown to a suitable place.

THERE IS NO NEED TO OVER REACT IMMEDIATELY AND CRASH A HELICOPTER WHICH IS STILL CAPABLE OF SAFE FLIGHT!!

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JAMMED OR LOSS OF THROTTLE CONTROL

INDICATIONS:  

1.  The THROTTLE WILL NOT MOVE

2.  THROTTLE MOTION HAS NO EFFECT ON MAP & RPM

ACTIONS: Very similar to a jammed collective. The collective can be used to make the helicopter descend.

Lowering the pitch will ensure RPM overspeed and vice versa, so there is a limit to the amount that the pitch can be lowered.  IAS can be used as in jammed collective. 

Again a magneto can be turned off if NECESSARY to make the machine finally descent.

If necessary the engine can be stopped and an autorotation carried out.  NOTE: first fly to a suitable area and burn off excess fuel to make the auto easier.

Remember you are more likely to break the helicopter in auto than using the IAS control procedure.

Sometimes with a throttle control failure the throttle may wind off requiring lowering of pitch to maintain RPM and maybe forced into auto or the throttle may wind on requiring a pitch increase to control RPM.

THIS WILL MAKE IT DIFFICULT to descend using the IAS control method.  At least it will be possible to stay in the air even if the engine is over boosting.

An auto may be inevitable but at least fly to a suitable area before entering the auto.  Turning off one magneto to reduce power may allow the use of an IAS control landing  but is unlikely if the helicopter is only moderately loaded!

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FIRE IN THE CABIN

Indications of this will be obvious.  If it is electrical turn off battery and generator, if the cause is not obvious, i.e. .. if the smoke is coming from a radio, pull the radio circuit breaker.  If the fire is caused by something else i.e. dropped cigarette, use the extinguisher and remember to open window and doors to get rid of smoke and extinguisher fumes.

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HYDRAULIC FAILURE

(a)  INDICATIONS: The cyclic will become stiff and suffer from feed back.  It will become easy to over control on the cyclic.  The collective, if fitted with hydraulics, will become stiff to operate.

(b)  ACTIONS:   

1.  Maintain the  I.A.S. to between 35 and 53 Kts using small firm cyclic corrections.

2.  Cycle the Hydraulic switch on the instrument panel ensure it is on. 

If the hydraulics are not restored turn off the hydraulic switch and leave it off. 

On helicopters with electric hydraulic switch pull the hydraulic circuit breaker to check if an electric malfunction is not the problem.  If this does not restore the hydraulics push in the circuit breaker and then turn off the hydraulics.  Electric power is required to turn OFF the hydraulics.

3.  Land within 20 minutes using a shallow approach with a short running landing.  The helicopter can be hovered quite successfully with hydraulics off if required.  The hovering attitude must be held closely with small early corrections.