At least it was still under warranty!

[Cyclic Hotline]

This story becomes more pointless with every passing sentence.

RCMP helicopter removed from N.B. sandbar after emergency landing

TABUSINTAC, N.B. (CP) - An RCMP helicopter forced to make an emergency landing on a sandbar off northeastern New Brunswick, was removed by barge on Monday.

It could be a week before investigators know what caused the aircraft to shake violently just before the pilot set it down late Saturday. Three officers aboard were not injured.

The helicopter was brought ashore and will be checked over for damage and the source of the mechanical failure.

The chopper went into service just last fall, replacing one that had been in use for 25 years.

It's still under warranty.

[407 Driver]

350B3, possibly a massive M/R overspeed (490 rpm?)

[Spunk]

Hi Bell407,

doesn't that only apply to the EC120?

[407 Driver]

I was told the aircraft reached a point over 490 Rpm, I'd expect that a B3 runs at 390 +/-, similar to a B2 ? So that equated to a 126% M/R speed.

An overspeed can happen to any aircraft.
If a FADEC or governor system goes bad, Zoom, up comes the M/R RPM.
The pilot controlled the overspeed, (or it went into an automatic shut-down situation, I'm not familiar with the B3 systems), he auto'd and all 3 on board are fine.

The aircraft can be repaired.

Well done !

[Firepilot]

I don't know anything about the accident, but here is what I know about the B-3 (I'm currently flying one and am very partial to it)


The B-3 has a different type of FADEC than Bell products. When you get a failure, the fuel contol freezes at the value at failure. Theoretically, you shouldn't be able to get an overspeed from any kind of FADEC (DECU) failure. You just revert to manual throttle manipulation (like a piston)
There has been a change made from the earlier B-3's. The twist grip has gone from having a manual override lock (to move the throttle past the "fly" position) to automatic lock disengage(servo of some sort) on the newer models. IMO this change was brought about because of numerous overspeeds caused by inadvertent disengagement of the manual lock while doing practice autorotations. (a major one happened in Alaska)

The helicopter's Vehicular Engine Multi-functional Display (VEMD) was queried to recover archived rotor data from the accident flight. The VEMD only records main rotor rpm to 511. An overspeed is defined by Turbomeca as 47,304 rpm of the power turbine, or 121%, of the standard maximum operating rpm of 39,095. At 511 main rotor rpm, the power turbine was operating at approximately 50,803 rpm. It is possible for the main rotor system to exceed the 511-recorded rpm, and for the power turbine to experience higher revolutions, but it will not be recorded in the VEMD. The accident helicopter's VEMD read-out indicated the maximum, 511-rpm.


NTSB Identification: ANC00LA132 .
The docket is stored in the Docket Management System (DMS). Please contact Public Inquiries
14 CFR Part 91: General Aviation
Accident occurred Saturday, September 23, 2000 in KETCHIKAN, AK
Probable Cause Approval Date: 2/7/2002
Aircraft: Eurocopter AS-350B-3, registration: N405AE
Injuries: 2 Uninjured.
Two commercial helicopter pilots, both certificated helicopter instructors, were in a turbine-powered helicopter practicing autorotations with a power recovery prior to touchdown. The flying pilot inadvertently activated the flight stop augmented fuel flow switch during a power recovery, and oversped the engine and main rotor. The other pilot joined him on the controls, and increased collective to reduce rotor rpm. The helicopter climbed abruptly to about 60 feet above the ground, where the tail rotor drive shaft separated. The engine subsequently lost power, and an autorotation was accomplished. Investigation disclosed that the engine and main rotor system had been exposed to significant overspeed conditions, resulting in a catastrophic failure of the turbine engine, and the tail rotor drive shaft coupling. The flight stop switch on the collective has no protective guard, and can be readily engaged, allowing the engine to enter the augmented fuel flow regime and, under certain conditions, causing the engine to overspeed. The switch has a history of inadvertent activation, and resultant engine overspeed events.

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:

The pilot's inadvertent activation of the collective flight stop/emergency fuel augmentation switch, which resulted in engine and main rotor overspeeds, thereby precipitating failures of the tail rotor drive shaft coupling and power turbine blades. A factor associated with the accident was the manufacturer's inadequate design of the flight stop switch, which has insufficient safeguards to preclude inadvertent activation.