Bell TH-1 N106SR

Summary

On 20 December 1989 at about 14:20 local time, a Bell TH-1 registered N106SR was involved in an accident near Creola, Alabama, 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

20 December 1989 at 14:20

Classification

Accident

Location

Creola, Alabama, United States

Coordinates

30.8894, -88.0004

Aircraft

Bell TH-1

Registration

N106SR

Category

Helicopter

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Other Work Use

Phase of flight

Not recorded

Route

Mt Vernon → Mobile

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

ATL90LA042

Nobody was injured.

THE LOSS OF ENGINE POWER DUE TO A #21 BEARING FAILURE. THE BEARING FAILED AS A RESULT OF INADEQUATE MAINTENANCE. A FACTOR IN THE ACCIDENT WAS THE PILOT OPERATING THE HELICOPTER WITHIN THE AVOID OPERATING ENVELOPE.

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

Read the full NTSB narrative

THE ENGINE FAILED WHILE THE PILOT WAS HOVERING AT 110 FT DURING AN EXTERNAL LOAD OPERATION. THE PILOT RELEASED THE LOAD AND AUTOROTATED INTO A SWAMPY AREA. ENGINE TEARDOWN SHOWED EVIDENCE OF SEIZURE AND HEAVY WEAR AT THE #21 BEARING ASSEMBLY ROLLER/SHAFT INTERFACE. METALLURGICAL EXAM REVEALED A BREAKDOWN OF THE TUNGSTEN CARBIDE AND COBALT COATING REPAIR. THE DETONATION GUN (DGUN) REPAIR BUILDUP ON THE BEARING/SEAL JOURNAL, SEO T53-LO-R0035, WAS USED IN 1969, AND CANCELED IN 1970. THE PROCEDURE WAS NOT APPROVED OR PRACTICED BY LYCOMING, AND THE MANUFACTURER RECOMMENDED THAT PARTS REPAIRED IAW THE SEO NOT BE INSTALLED IN ENGINES. THE PILOT WAS OPERATING WITHIN THE 'AVOID OPERATION' AREA OF THE AIRSPEED VELOCITY CHART.

Quoted verbatim from the NTSB record.