Pilot Debrief

Bob Frederick Titan T-51 near Goodyear, AZ — 2017-06-04

Final reportWPR17LA121
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Date
2017-06-04
Location
Goodyear, AZ, USA
Airport
GYR
Aircraft
Bob Frederick Titan T-51
Registration
N51FB
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Initial climb

Probable cause

Failure of the propeller speed reduction gearbox input drive gear during the airplane’s initial climb for reasons that could not be determined due to extensive damage.

NTSB narrative

The airline transport pilot indicated that, immediately after takeoff for the local flight, the experimental, amateur-built airplane began to vibrate. As he transitioned the airplane to the downwind leg, the vibration increased, and the engine then experienced an overspeed and lost all power. The cockpit filled with smoke and the pilot subsequently performed a forced off-airport landing, which resulted in substantial damage to the left wing and aft fuselage. The airplane had accrued about 43 flight hours since its construction, which was completed about 2 years before the accident. Examination of the propeller speed reduction gearbox revealed that the teeth of the input drive gear had separated, which caused a loss of drive continuity to the propeller. The drive and idler gears did not appear to meet the manufacturer's case hardness requirements; however, evidence suggests that the gearbox had undergone severe heat buildup during the failure sequence, which may have subsequently altered the hardness. Oil starvation or exhaustion likely did not occur, as the gearbox bearings were intact and largely undamaged. Due to damage sustained to the gears, an accurate assessment of the initial failure mode could not be determined. Thus, the investigation could not determine the reason for the failure of the propeller speed reduction gearbox input drive gear.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Pilot could have aborted takeoff upon initial vibration detection.

NTSB coding

Evidence available

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

Docket documents6

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