Cessna 207 N1673U

Summary

On 20 June 1998 at about 03:25 local time, a Cessna 207 registered N1673U, operated by Inland Aviation Services Inc., was involved in an accident near Holy Cross, Alaska, United States. 4 people were 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

20 June 1998 at 03:25

Classification

Accident

Location

Holy Cross, Alaska, United States

Coordinates

62.1810, -159.8398

Aircraft

Cessna 207

Registration

N1673U

Category

Airplane

Engines

1

Operator

Inland Aviation Services Inc.

Operating rule

Part 135: Air Taxi & Commuter

Purpose of flight

Unknown

Phase of flight

Not recorded

Route

Grayling → Bethel

Aircraft damage

Substantial

Weather

VMC

Light

Day

NTSB number

ANC98LA078

Nobody was injured.

The improper installation/undertorquing of the engine crankcase bolts by company maintenance personnel, and a subsequent fracture of the engine crankshaft. A factor in the accident was unsuitable terrain for a forced landing.

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

Read the full NTSB narrative

The pilot and three passengers, departed on an air taxi flight over remote terrain. While in cruise flight about 2,200 feet, the engine oil pressure began to drop, and the engine oil temperature began to rise. The pilot decided to divert to the nearest airport. The engine quit running, and the pilot selected an emergency landing area on a sand bar along a river that contained several willow trees. During the landing, the airplane received damage to the wings and fuselage. The engine had accrued 1,491 hours since an overhaul. During that time, seven engine cylinder changes were performed by company maintenance personnel. An examination of the engine revealed the crankshaft was broken along the aft, lower edge of the number two cheek journal, at the forward radius of the number two main bearing journal. The fracture line was straight and flat, through the full dimension of the number two cheek journal, and was oriented perpendicular to the longitudinal axis of the crankshaft. The number two main bearing was broken and flattened. The number two main bearing saddle was flattened and distorted. The left and right engine case halves mating surface exhibited galling/fretting at the number two main journal bolt holes.

Quoted verbatim from the NTSB record.