Pilot Debrief

CESSNA 180 near California City, CA — 2016-05-13

Final reportWPR16LA108
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Date
2016-05-13
Location
California City, CA, USA
Airport
L71
Aircraft
CESSNA 180
Registration
N9370C
Category
Airplane
Highest injury
Minor
Fatalities
0
Phase of flight
Landing

Probable cause

A directional upset on landing due to a thermally induced atmospheric disturbance, which the pilot was unable to successfully counter due to improperly set rudder travel limits.

NTSB narrative

The day before the accident, a satisfactory annual inspection was completed for the tailwheel-equipped airplane, and the owner/pilot conducted an uneventful flight later that day. The following day, he flew the airplane to another airport to obtain a cost estimate for some "cosmetic" maintenance. The flight was uneventful, but as the airplane touched down about 1315 local time on the desert airport runway, it bounced and then touched down again. On the second touchdown, the airplane veered sharply left, and the pilot was unable to regain directional control. The airplane nosed over onto its back when it exited the paved edge of the runway. Detailed examination of the airplane did not reveal any mechanical reasons for the post-touchdown left swerve. However, the rudder travel stops were found to be set so that the rudder travel limits were 16° right and 13° left, instead of the manufacturer-specified value of 24° in each direction. After that examination, the pilot reported that the "cosmetic" maintenance he was planning was to correct a top-to-bottom curvature (bow) in the rudder that resulted in an approximate 1.5-inch misalignment between the top and bottom of the rudder. According to the pilot, that bow was either a direct result of a 1974 accident or the consequent improper repair. Because the airplane had been operated uneventfully for 42 years with the deformed rudder, it is unlikely that this deformity caused the left veer. The airplane likely initially veered left due to an encounter with an atmospheric phenomenon common in desert environments on hot afternoons. These thermally induced air disturbances tend to be strong, highly localized, and short term but unpredictable and often undetectable. Thus, the pilot had no means to detect the air disturbance until he encountered it and then the improperly set rudder travel limits significantly reduced his ability to counter the resulting directional upset.

Analysis

Primary failure mode
Loss of control
First missed decision gate
Pilot could have addressed rudder issue before attempting to land.

NTSB coding

Evidence available

  • 8 docket documents
View NTSB final reportView NTSB docket

Docket documents8

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