Schweizer 269C-1 N345MH

Summary

On 26 May 2012 at about 17:20 local time, a Schweizer 269C-1 registered N345MH, operated by My Sky LLC, was involved in an accident near Chesterfield, Missouri, United States. One person was on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

26 May 2012 at 17:20

Classification

Accident

Location

Chesterfield, Missouri, United States

Nearest airport

Spirit of St Louis (SUS)

Coordinates

38.6622, -90.6519

Aircraft

Schweizer 269C-1

Registration

N345MH

Category

Helicopter

Engines

1

Operator

My Sky LLC

Operating rule

Part 91: General Aviation

Purpose of flight

Instructional

Phase of flight

Not recorded

Route

Chesterfield → Chesterfield

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

CEN12LA353

Nobody was injured.

The undercharged and overcharged landing gear dampers, which allowed initiation of the ground resonance event from which the pilot was unable to recover due to his limited experience in helicopters. Contributing to the accident was the ineffective damper inspection conducted by the operator’s maintenance personnel and the improper overhaul procedure by the overhaul facility that resulted in overcharged dampers being provided to the operator. Also contributing was the lack of any final acceptance testing criteria for the dampers in the manufacturer’s overhaul procedure manual.

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB narrative

The pilot reported that the helicopter started to shake as he increased power for takeoff on the solo instructional flight. He reduced engine power, but the oscillations became stronger and ultimately uncontrollable, resulting in substantial damage to the main and tail rotor blades, partial separation of the main rotor mast from the aft fuselage structure, and partial separation of the tail boom from the fuselage. The pilot shut down the engine and exited the helicopter. The pilot was receiving training for the addition of a helicopter rating and was operating the helicopter under the authority of a logbook solo endorsement. Postaccident testing revealed that all four landing gear dampers failed to meet the manufacturer’s specifications. The forward dampers were undercharged, while the aft dampers were overcharged. Maintenance records indicated that the aft dampers had been replaced with overhauled units about 1 month before the accident. The forward dampers had not been replaced. Maintenance procedures required periodic inspection of the landing gear dampers, and the operator stated that the inspection procedure was accomplished after installation of the overhauled dampers. A review of the overhaul procedure for the landing gear dampers revealed that the procedure did not provide for functional testing of the dampers following overhaul, which would have identified the out-of-specification condition before installation.

Quoted verbatim from the NTSB record.