Auman Jl T-51 N512JA

Summary

On 11 December 2012 at about 21:45 local time, a Auman Jl T-51 registered N512JA was involved in an accident near Dekalb, Illinois, United States. One person was on board and one was seriously injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

11 December 2012 at 21:45

Classification

Accident

Location

Dekalb, Illinois, United States

Nearest airport

De Kalb Taylor Municipal Airpo (DKB)

Coordinates

41.8893, -88.7508

Aircraft

Auman Jl T-51

Registration

N512JA

Category

Airplane

Engines

1

Operator

Not recorded

Operating rule

Part 91: General Aviation

Purpose of flight

Flight Test

Phase of flight

Not recorded

Route

Dekalb → Dekalb

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

CEN13LA103

1 person was seriously injured.

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

Quoted verbatim from the NTSB record. This site does not paraphrase or interpret it.

Read the full NTSB 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.

Quoted verbatim from the NTSB record.