Pilot Debrief

Piper PA46 near San Jose, CA — 2020-02-28

Final reportWPR20LA104
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Date
2020-02-28
Location
San Jose, CA, USA
Airport
SJC
Aircraft
Piper PA46
Registration
N304LA
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Approach

Probable cause

The failure to properly service the hydraulic power pack prevented a normal landing gear extension. Contributing to the accident was the failure of the landing gear emergency release valve to function properly for reasons that could not be determined based on available information.

NTSB narrative

Despite several attempts, the airplane’s landing gear was unable to be extended and locked during the approach to the destination airport. The flight instructor elected to divert to a more suitable airport where they could circle while they tried to extend the landing gear. Continued attempts by the pilot receiving instruction and the flight instructor to troubleshoot the problem and extend the landing gear were unsuccessful. The flight instructor subsequently landed the airplane with the landing gear retracted. Postaccident examination of the land gear system revealed that the hydraulic power pack used to operate the landing gear had a lack of adequate hydraulic fluid in the reservoir, consistent with a hydraulic line being disconnected to release the landing gear during recovery and not reconnected. Therefore, the hydraulic fluid level in the reservoir could not be determined prior to the accident, however, . once properly serviced with hydraulic fluid, the power pack functioned appropriately. It’s likely the power pack was not serviced to the proper level during the accident flight, which resulted in the failure of the landing gear to extend. During initial testing, the landing emergency release valve did not release hydraulic pressure when activated. Two bolts located on the valve bracket were missing lockwire. The bolts are supposed to be torqued and safety wired to prevent movement of the valve lever setting. The valve bracket and valve lever were at the extreme setting, which would produce minimal activation of the valve. The loose valve bracket bolts could affect the valve lever position by allowing the valve bracket to slide when actuating the valve. Once the valve bracket bolts were appropriately secured, the valve functioned properly with no anomalies noted. It’s most likely the valve bracket bolts were not installed properly with lockwire. Although the investigation identified other potential causes of the valve not functioning properly, including the rigging of the actuation cable to the landing emergency release valve and the valve possibly not being fully set to the closed position at an unknown time, the investigation was unable to determine the exact cause of the landing gear emergency release valve failure.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Pilot could have opted for an earlier diversion to a closer airport.

NTSB coding

Evidence available

  • 4 docket documents
View NTSB final reportView NTSB docket

Docket documents4

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