Pilot Debrief

BEECH C90A near Roanoke, VA — 2012-11-20

Final reportERA13LA065
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Date
2012-11-20
Location
Roanoke, VA, USA
Airport
ROA
Aircraft
BEECH C90A
Registration
N702DK
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Approach

Probable cause

The failure of the right main landing gear bearing actuator support brackets. Contributing to the accident was the owner's and operator's failure to comply with the airplane manufacturer's mandatory service bulletin and the Federal Aviation Administration's failure to issue an airworthiness directive.

Contributing factors

Contributing to the accident was the owner's and operator's failure to comply with the airplane manufacturer's mandatory service bulletin and the Federal Aviation Administration's failure to issue an airworthiness directive.

NTSB narrative

During the downwind leg of the traffic pattern at the destination airport, the pilots lowered the landing gear. The pilot then noticed that the right main landing gear (MLG) was not down and locked in position for landing. The flight crew made multiple attempts to get a down-and-locked indication without success, so the pilot decided to abort the landing and divert to another airport with longer runways. After executing the manual gear extension checklist, the flight crew made a low pass at the diversion airport, and the air traffic controller in the control tower advised that the landing gear appeared to be in the down position. During the landing, the touchdown was normal, and the airplane slowed normally; however, as the airplane exited the runway, the right MLG collapsed. Examination of the wreckage revealed that the right wing, right nacelle, and right wheel well had received substantial damage and that the right MLG, after collapsing, had punctured the right nacelle fuel tank. The right MLG bearing actuator support bracket was made of aluminum. Examination of the right MLG revealed that the right MLG bearing actuator support bracket was broken and had separated from its mounting position. Multiple cracks in the bracket were visible, and, at the microscopic level, the cracks had shiny surfaces indicative of abrasion, and overload regions with a cloudy appearance. Essentially, with each cycle, whether it was with extension of the landing gear, retraction of the landing gear, or landing itself, the cracks were subjected to loading which caused them to continue to propagate until the entire assembly reached a point at which structural integrity was no longer present to hold the landing gear actuator. In December 2003, the airplane manufacturer issued a mandatory service bulletin to replace the right and left aluminum MLG bearing actuator support brackets with steel brackets and specified that the replacement of the brackets be accomplished "as soon as possible," but "no later than the next scheduled inspection, the next 200 flight hours or 24 months." The airplane manufacturer also requested that the Federal Aviation Administration (FAA) issue an Airworthiness Directive (AD) based on the service bulletin. However, the FAA did not find an "unsafe condition" and did not issue an AD, which would have made compliance with the service bulleting mandatory. Review of the airplane's maintenance records confirmed that the airplane owner and the operator had not had the new steel brackets installed. Further, the FAA has not issued an AD for the MLG bearing actuator support brackets.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Failure to replace aluminum MLG actuator support brackets as per MSB.

NTSB coding

Evidence available

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

Docket documents13

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