Hughes 269C N8376F

Summary

On 5 August 1994 at about 22:15 local time, a Hughes 269C registered N8376F, operated by James C. Hobbs, was involved in an accident near Puunene, Maui, Hawaii, United States. 2 people were 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

5 August 1994 at 22:15

Classification

Accident

Location

Puunene, Maui, Hawaii, United States

Coordinates

Not recorded

Aircraft

Hughes 269C

Registration

N8376F

Category

Helicopter

Engines

1

Operator

James C. Hobbs

Operating rule

Part 91: General Aviation

Purpose of flight

Instructional

Phase of flight

Not recorded

Route

Kahului, Maui → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

LAX94LA306

Nobody was injured.

the improper overhaul of the red blade main rotor damper, and the inadequate maintenance condition of the other rotor dampers and the landing gear dampers, which led to an uncorrectable ground resonance vibration and a subsequent rollover.

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

Read the full NTSB narrative

THE STUDENT WAS PERFORMING A PRACTICE AUTOROTATION AND AT 10 FEET HE BEGAN TO INCREASE THE COLLECTIVE TO CUSHION THE TOUCHDOWN. THE CFI SAID THE MAIN ROTOR RPM WAS LOW AND HE ADDED THROTTLE TO TOUCHDOWN WITH POWER. A GROUND RESONANCE VIBRATION BEGAN AND HE LIFTED OFF THE GROUND. THE VIBRATION CONTINUED AND HE ROLLED THE THROTTLE OFF AND SET THE HELICOPTER ON THE GROUND, THEN IT ROLLED OVER ON ITS SIDE. THE LANDING GEAR DAMPERS AND MAIN ROTOR DAMPERS WERE REMOVED AND TESTED AT THE FACTORY. THE RIGHT REAR AND LEFT FRONT MAIN LANDING GEAR DAMPERS HAD CHARGE PRESSURES BELOW ACCEPTABLE FACTORY SPECS. THE RIGHT FRONT AND LEFT REAR DAMPERS WERE FOUND TO BE WITHIN FACTORY SPEC RANGES. ALL THREE MAIN ROTOR DAMPERS WERE FOUND TO BE ADJUSTED TO EXCESSIVE FRICTION TORQUE VALUES. THE RED BLADE DAMPER WAS ASSEMBLED INCORRECTLY WITH A PLATE STACK UP IMPROPER FOR ANY VERSION OF THE DAMPER ASSEMBLY. THE HELICOPTER WAS IN STORAGE FOR 2 YEARS PRIOR TO JUNE 1994, WHEN IT WAS LEASED TO THE OPERATOR. THE RED BLADE DAMPER HAD BEEN REMOVED FROM ANOTHER HELICOPTER, OVERHAULED, AND PLACED IN SPARE PARTS INVENTORY, THEN PUT ON THE RED BLADE ON JULY 20, 1994.

Quoted verbatim from the NTSB record.