Bell UH-1E N138US

Summary

On 4 November 1989 at about 16:15 local time, a Bell UH-1E registered N138US, operated by Gilman D. Christopher, was involved in an accident near Mesa, Arizona, United States. 2 people were on board and nobody was injured. The aircraft was destroyed. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

4 November 1989 at 16:15

Classification

Accident

Location

Mesa, Arizona, United States

Coordinates

33.4390, -111.7602

Aircraft

Bell UH-1E

Registration

N138US

Category

Helicopter

Engines

1

Operator

Gilman D. Christopher

Operating rule

Part 137: Agricultural

Purpose of flight

Aerial Application

Phase of flight

Not recorded

Route

Queen Creek → Unknown

Aircraft damage

Destroyed

Weather

VMC

Light

Day

NTSB number

LAX90DUJ05

Nobody was injured.

THE INFLIGHT SEPARATION OF THE TAIL ROTOR DUE TO IMPROPER MAINTENANCE PROCEDURES AND THE INSTALLATION OF INCORRECT ATTACHMENT HARDWARE ON THE TAIL ROTOR BLADE PITCH CHANGE LINKAGES.

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

Read the full NTSB narrative

INVESTIGATION DISCLOSED THAT THE TAIL ROTOR SEPARATED FROM THE HELICOPTER IN FLIGHT. THE TAIL ROTOR ASSEMBLY WAS SENT TO THE MANUFACTURER FOR ANALYSIS. ON TAIL ROTOR BLADE 'A' THE BOLT, NUT AND ASSOCIATED HARDWARE THAT ATTACHED THE PITCH CHANGE LINK TO THE BLADE GRIP WERE MISSING. THE BOLT BUSHING WAS WORN BEYOND THE SERVICE LIMITS THAT MANDATED REPLACEMENT. ON BLADE 'B' THE ATTACHING BOLT, NUT AND HARDWARE WERE DETERMINED TO BE THE WRONG SIZE. IN ADDITION, THE WRONG SPACER WAS ATTACHED TO THE BOLT. FOUR MORE WASHERS THAN ALLOWED WERE UNDER THE TRAILING EDGE BLADE RETAINING BOLT NUT. ACCORDING TO THE PREFLIGHT INSPECTION REQUIREMENTS, THE DISCREPANCIES ON THE BLADE 'A' BUSHING AND THE INCORRECT HARDWARE ON THE BLADE 'B' PITCH CHANGE LINK SHOULD HAVE BEEN DETECTED DURING THE DAILY INSPECTION EVENT.

Quoted verbatim from the NTSB record.