Pilot Debrief

MOONEY AIRCRAFT CORP. M20K near Augusta, GA — 2011-07-18

Final reportERA11FA406
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Date
2011-07-18
Location
Augusta, GA, USA
Airport
AGS
Aircraft
MOONEY AIRCRAFT CORP. M20K
Registration
N777CV
Category
Airplane
Highest injury
Fatal
Fatalities
1
Phase of flight
Initial climb

Probable cause

The pilot’s decision to fly the airplane after maintenance personnel advised him that the airplane should not be flown because the pilot provided an incorrect propeller for installation and the subsequent failure of the propeller attachment bolts and the separation of the propeller.

NTSB narrative

Maintenance personnel reported that, 2 days before the accident, they were hired by the pilot to prepare the airplane for a maintenance ferry flight following a gear-up landing. While inspecting the airplane, the mechanic noted that the three-blade propeller was bent, so he removed it. Subsequently, the pilot provided maintenance personnel with a two-blade propeller, which they installed. However, when the mechanic attempted to replace the spinner, it would not fit properly. Therefore, he did not sign off the logbooks and advised the pilot that the airplane should not be flown. Review of the airplane's records revealed that the airplane had a supplemental type certificate for an engine conversion kit that required a three-blade propeller. On the day of the accident, another mechanic conducted a run-up of the engine and noted that the propeller was not working correctly. The supplier of the two-blade propeller advised the mechanic that the airplane should not be flown in that condition. The mechanic discussed the anomaly with the pilot and advised him not to fly the airplane until the issue was resolved. The pilot acknowledged the discrepancy but chose to fly the airplane. Shortly after takeoff, witnesses observed the propeller separate from the airplane. Subsequently, the airplane spiraled to the ground in a nose-down attitude. Examinations revealed that the propeller attachment bolts had failed, which resulted in the separation of the propeller from the airplane. Five of the six propeller mounting studs exhibited evidence of high-stress fatigue cracking, which indicates that a severe spectrum of cyclic loading in the propeller/engine system occurred, likely as the result of using an unapproved propeller on the airplane.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Pilot should not have flown the airplane with known propeller control issues.

NTSB coding

Evidence available

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

Docket documents33

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