Pilot Debrief

CESSNA 172RG near Kissimmee, FL — 2011-11-08

Final reportERA12LA070
Sign in to save
Date
2011-11-08
Location
Kissimmee, FL, USA
Airport
ISM
Aircraft
CESSNA 172RG
Registration
N5095V
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Landing

Probable cause

A fatigue failure of the right main landing gear pivot assembly, which prevented the landing gear from extending.

NTSB narrative

The pilot was not able to obtain a positive gear down-and-locked indication and noticed that the right main landing gear (MLG) only extended about halfway down. After unsuccessful troubleshooting efforts, he performed an emergency gear-up landing, which resulted in substantial damage to the underside of the fuselage. Examination of the landing gear system revealed that the stub shaft of the right MLG pivot assembly was fractured and exhibited characteristics consistent with a torsional fatigue fracture containing multiple origins. Before the accident flight, a company mechanic observed some hydraulic fluid on the MLG leg and assumed that there was a leak from the pivot gear O-rings, which he replaced. The Federal Aviation Administration previously issued an airworthiness directive (AD), which included an inspection of MLG pivot assemblies for cracks, in accordance with a manufacturer's service bulletin. The AD did not call for repetitive inspections. At the time of the accident, the airplane had been operated for about 7,755 total hours and about 1,800 hours since the time of AD compliance. The airplane service manual contained a supplemental inspection that included initial visual and eddy current inspections of the MLG pivot assembly for cracks in the spline area at 3,000 hours in service with repeated inspections every 500 hours thereafter. The visual and eddy current inspections had not been nor were they required to be performed on the accident airplane.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Failure to perform required inspections on landing gear pivot assembly.

NTSB coding

Evidence available

  • Photos
  • 13 docket documents
View NTSB final reportView NTSB docket

Docket documents13

Related mishaps