Cessna T188C N4629J

Summary

On 27 September 2001 at about 14:05 local time, a Cessna T188C registered N4629J, operated by Addison Spraying Service, was involved in an accident near Aiken, Texas, United States. One person was on board and nobody was injured. The aircraft was substantially damaged. The NTSB has published a probable cause for this accident; it is quoted in full below.

Date

27 September 2001 at 14:05

Classification

Accident

Location

Aiken, Texas, United States

Coordinates

34.1233, -101.5183

Aircraft

Cessna T188C

Registration

N4629J

Category

Airplane

Engines

1

Operator

Addison Spraying Service

Operating rule

Part 137: Agricultural

Purpose of flight

Aerial Application

Phase of flight

Not recorded

Route

Aiken → Unknown

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

FTW01LA210

Nobody was injured.

the application of silicon sealant to the crankcase mating surfaces by maintenance personnel, which resulted in improper torque on the bolts which mate the crankcase halves, vibration, and the subsequent failure of the #2 main crankshaft bearing. A factor was the lack of suitable terrain for the forced landing.

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

Read the full NTSB narrative

The pilot was maneuvering the agricultural airplane to enter a field and commence spraying, when at 120 feet agl, the engine lost power. The pilot attempted to restart the engine; however, the engine did not restart. During the ensuing forced landing, the airplane contacted circular rows of cotton, before coming to rest upright. The engine was examined at the manufacturer's facility and silicon sealant was observed on the base flanges of the #1, #2, #4, and #6 cylinders and on the crankcase mating surfaces. Fretting was observed on the base flanges of the cylinders, on the mating surface of the crankcase halves, and on the main bearing bosses. The #2 main bearing was observed fragmented and the bearing's bore was cracked and damaged. Additionally, it was observed that the crankshaft was fractured between the #2 main bearing and #3 crankshaft cheek. According to a TCM metallurgist, the fatigue fracture's origin was determined to be at the aft radius of the #2 main bearing. The silicon sealant prevented proper torqueing of the bolts that mate the crankcase halves and led to vibration at the crankcase mating surfaces. The #2 main bearing then shifted and failed, resulting in a loss of engine power.

Quoted verbatim from the NTSB record.