Accident Auman T-51 N512JA,
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ASN Wikibase Occurrence # 151156
 
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Date:Tuesday 11 December 2012
Time:15:45
Type:Auman T-51
Owner/operator:Private
Registration: N512JA
MSN: 39
Total airframe hrs:5 hours
Engine model:Honda J35 A6
Fatalities:Fatalities: 0 / Occupants: 1
Aircraft damage: Substantial
Category:Accident
Location:Near De Kalb Taylor Municipal Airport - KDKB, De Kalb, IL -   United States of America
Phase: Take off
Nature:Test
Departure airport:Dekalb, IL (DKB)
Destination airport:Dekalb, IL (DKB)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The experimental amateur-built airplane experienced a total loss of engine power during a phase one test flight. The pilot performed a forced landing on a field where airplane nosed-over due to the rough condition of the field that precluded a normal landing rollout.
Before the phase 1 test flight, the pilot had returned the engine to the kit manufacturer for repair due to leaking engine coolant. Postaccident examination of the engine revealed catastrophic damage; the engine head bolt had been tighten above the engine manufacturer’s torque values, which indicated that the kit manufacturer used excessive torque on the head bolts in an attempt to repair coolant leakage through the engine head.
The postaccident examination showed that the engine was assembled with cast and not forged pistons, which should be used in high performance applications. The bending and thread damage on the intact connecting rod bolt for the forward right cylinder and the mating thread damage in the connecting rod were consistent with the bolt backing out until it sheared the remaining threads. Another bolt that backed out of position was also present on the connecting rod in the middle right position. Measurements of cylinder wall carbon lines showed a variance in size, which may have been due to hydraulic lock related bending of the connecting rods.


Probable Cause: The improper engine overhaul by the airplane kit manufacturer, which resulted in a catastrophic engine failure.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: CEN13LA103
Status: Investigation completed
Duration: 1 year and 9 months
Download report: Final report

Sources:

NTSB
FAA register: http://registry.faa.gov/aircraftinquiry/NNum_Results.aspx?NNumbertxt=512JA

Location

Revision history:

Date/timeContributorUpdates
12-Dec-2012 01:50 gerard57 Added
12-Dec-2012 09:19 Geno Updated [Time, Aircraft type, Registration, Cn, Location, Departure airport, Source, Narrative]
21-Dec-2016 19:28 ASN Update Bot Updated [Time, Damage, Category, Investigating agency]
28-Nov-2017 14:01 ASN Update Bot Updated [Other fatalities, Nature, Departure airport, Destination airport, Source, Narrative]

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