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Presented to: International Helicopter Safety Symposium, September 26-29, 2005, Montreal

Engineering Assumption versus Operational Reality: Repeated Lift Operation.

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Heli-logging

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Helicopters work in cycles

• For pleasure and corporate helicopters there are 4 cycles per hour.

• For heli-logging and firefighting there are 20 to 30 cycles per hour.

 

• Some manufacturers do not accept the facts of cycles nature.

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Heli-logging as part of Repetitive Lift Operations (RLO)

• Since the late seventies some helicopters have been dedicated to Repetitive Lift Operations (RLO) and there have been some significant accidents because of component malfunctions.

• During RLO operations there can be 10 times more events than anticipated as normal operations;

• There is a significant number of helicopters dedicated to RLO operations.

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Torque & Hook Weight over TimePleasure Flight & Anticipated Usage

Torque & Hook Weight over Time

%

100

80

60

40

20

0O 2 4 6 8 10 12 14 Time (min)

torque

Hook weight

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Torque & Hook Weight over TimeHeli-logging

% Torque & Hook Weight over Time100

60

40

20

025 50 75 100 125 150

Time (sec) torque

hook weight

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Torque over timefor pleasure and heli-logging

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Real application versus certification spectrum

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Aerospatiale 315B Free Wheel Unit

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S-61 Roller damage

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S-61 Calm shaft

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Conclusions

• There is a need to enhance traceability and history of the critical components.

• There is a need for common cycle definitions with simple accounting methods.

• Critical components replacement and maintenance should be based on operational cycles versus flight hours.