Advises Pilots That Such Accidents Are Avoidable

Robinson Helicopter has released a safety alert following persistent reports of low-G mast bumping accidents in R44 and R66 helicopters.

Mast bumping is contact between an inner part of a main rotor blade or a rotor hub and the main rotor drive shaft (or ‘mast). Mast bumping can result in the helicopter breaking up in flight.

Robinson's R44 aircraft have been placed on a watch list by the New Zealand Transport Accident Investigation Commission because of the accidents.

In its safety alert Robinson says that the accidents are "entirely avoidable by using good pilot judgement" and adhering to certain operating procedures. Those include:

• Always avoid cyclic pushover maneuvers which could cause low-G, particularly following a cyclic pull-up. Initiate descents with collective, not forward cyclic.
• Apply gentle aft cyclic as soon as low-G (a lightweight feeling) is recognized. Do not wait until for a right roll to begin.
• Do not overreact to turbulence.
• Slow down in turbulence

Robinson has added a yellow precautionary operating range to the R44 and R66 airspeed indicators because they are capable of high speeds when lightly loaded. Maximum recommended cruise speed is 110 KIAS. "Speeds above 110 KIAS are not recommended except in smooth air with the pilot's attention fully focused on flying," the safety alert states.

(Image from file)

FMI: Full Safety Alert