Wsk Pzl Mielec M-18A N495WP

Summary

On 26 July 2004 at about 20:26 local time, a Wsk Pzl Mielec M-18A registered N495WP, operated by United States Forest Service, was involved in an accident near Burns, Oregon, 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 July 2004 at 20:26

Classification

Accident

Location

Burns, Oregon, United States

Coordinates

43.8528, -119.1817

Aircraft

Wsk Pzl Mielec M-18A

Registration

N495WP

Category

Airplane

Engines

1

Operator

United States Forest Service

Operating rule

Part 137: Agricultural

Purpose of flight

Aerial Application

Phase of flight

Not recorded

Route

Burns → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

SEA04TA147

Nobody was injured.

The improper installation of the throttle linkage clevis to the throttle control arm by unknown maintenance personnel. Contributing factors were the nylon lock nut separating from its' bolt, which permitted the throttle cable to disconnect from the throttle control arm, and the fence post.

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

Read the full NTSB narrative

The pilot was attempting to climb following a fire retardant drop. When he moved the throttle forward, the engine did not respond. The airplane started loosing altitude, and the pilot performed a forced landing to an open plateau. During the landing, the throttle would not retard all the way. In order to land the airplane, the pilot turned the fuel selector to the off position. During the landing roll, the left wing impacted a fence pole bending ribs and wrinkling the aileron. Post accident examination revealed that the bolt normally connecting the throttle linkage clevis to the throttle arm was missing. The investigating team examined a sister aircraft from the same provider. They found that a nylon lock nut had been installed on the clevis bolt, and it was loose enough to be removed without the aid of any tools. The industry standard, found in FAA Advisory Circular AC43.13-1B, chapter 7, section 4, paragraph 7-64, states that nylon locking nuts should not be used with rotating components or assemblies. It further states that nylon and/or fiber nuts are highly susceptible to wear from repetitive use and from high heat applications.

Quoted verbatim from the NTSB record.