Hiller UH-12C N9739C

Summary

On 24 October 1998 at about 16:30 local time, a Hiller UH-12C registered N9739C was involved in an accident near Clinton, Iowa, 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

24 October 1998 at 16:30

Classification

Accident

Location

Clinton, Iowa, United States

Coordinates

41.8395, -90.2293

Aircraft

Hiller UH-12C

Registration

N9739C

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Business

Phase of flight

Not recorded

Route

Clinton → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

CHI99LA012

Nobody was injured.

the failure of the 90 degree gearbox for reasons undetermined. Factors were the failure of the gearbox, and it not being possible for the pilot to maintain control of the aircraft.

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

Read the full NTSB narrative

During cruise flight the helicopter suffered a loss of tail rotor authority. The pilot initiated an autorotational landing; however, during the approach he lost all control of the aircraft. An inspection of the tail rotor gearbox after the accident revealed a failure of the 90 degree gearbox. The log books indicated an overhaul 195 hours prior to the accident with no other maintenance on the gearbox noted. An inspection of the helicopter was conducted one month prior to the accident and the helicopter had accumulated about 33 hours since that inspection.

Quoted verbatim from the NTSB record.