Piper PA-18-150 N4473A

Summary

On 11 October 1999 at about 00:05 local time, a Piper PA-18-150 registered N4473A was involved in an accident near Granite, Oklahoma, United States. 2 people were on board and 2 were seriously injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

11 October 1999 at 00:05

Classification

Accident

Location

Granite, Oklahoma, United States

Nearest airport

Twin Lakes Ranch Airport (810K)

Coordinates

34.9596, -99.3701

Aircraft

Piper PA-18-150

Registration

N4473A

Category

Airplane

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Personal

Phase of flight

Not recorded

Aircraft damage

Substantial

Weather

VMC

Light

Night/Bright

NTSB number

FTW00LA010

2 people were seriously injured.

Corrosion failure of the fuselage support tubing below the right wing forward attach fitting due to inadequate maintenance.

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

Read the full NTSB narrative

The airplane was destroyed upon impact with terrain following a loss of control during the takeoff/initial climb. Severe corrosion was found at two structural tube clusters (one with a windshield pillar) located directly below the right wing forward and aft attach fittings. The portion of the forward structure available for carrying loads prior to the accident was less than 30% of the circumference of the pillar tube. Deformation associated with the separation of the pillar tube indicates that the pillar failed under compression loads. The manufacturer's representative stated that the 'windshield pillar is normally subjected to a tensile load during flight.' It is possible that compression loads generated during the takeoff roll led to a compression failure of the pillar. This failure would have changed the lift characteristics of the wing since the separation point was directly below the right wing forward attach fitting. The most recent annual inspection was performed in January 1999; the maintenance entry for the annual stated, in part, 'treated steel tubing as required.' In June 1999, a major repair was made to a tube cluster in the aft fuselage area 'due to external rust through from past acid spill.'

Quoted verbatim from the NTSB record.