Mitsubishi MU-2-60 N66LA

Summary

On 18 August 1992 at about 09:58 local time, a Mitsubishi MU-2-60 registered N66LA, operated by Epps Air Service, was involved in an accident near Philadelphia, Pennsylvania, United States. 2 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

18 August 1992 at 09:58

Classification

Accident

Location

Philadelphia, Pennsylvania, United States

Nearest airport

Northeast Philadelphia (PNE)

Coordinates

40.0705, -75.0008

Aircraft

Mitsubishi MU-2-60

Registration

N66LA

Category

Airplane

Engines

2

Operator

Epps Air Service

Operating rule

Part 135: Air Taxi & Commuter

Purpose of flight

Unknown

Phase of flight

Not recorded

Route

Teterboro → Cleveland

Aircraft damage

Substantial

Weather

VMC

Light

Night/Dark

NTSB number

NYC92LA166

Nobody was injured.

THE IN-FLIGHT SEPARATION OF A PROPELLER BLADE AS A RESULT OF FATIGUE CRACKING INITIATED FROM MULTIPLE SITES LOCATED AT CORROSION PITS IN THE BALANCING HOLE. CONTRIBUTING FACTORS IN THE ACCIDENT WERE: THE FAILURE TO DETECT THE CORROSION DURING THE LAST OVERHAUL PROCEDURE; AND A COMPLETE LOSS OF ELECTRICAL POWER AS RESULT OF THE SEPARATED BLADE BREAKING THE ELECTRICAL LINES.

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

Read the full NTSB narrative

AT 6000 FEET MSL, WHILE IN CRUISE FLIGHT, A PROPELLER BLADE FROM THE LEFT PROPELLER ASSEMBLY SEPARATED IN-FLIGHT, PENETRATED THE FUSELAGE, BREAKING ELECTRICAL LINES AND CAUSING A LOSS OF ELECTRICAL POWER. AT THE TIME THE AIRPLANE WAS IN IMC, SO THE PILOT ELECTED TO TURN 180 DEGREES IN AN ATTEMPT TO FLY TO AN AREA OF BETTER WEATHER. HE FLEW WITHOUT ELECTRICAL POWER OR MOST OF THE INSTRUMENTS FOR ABOUT 40 MINUTES, UNTIL REACHING AN AREA OF CLEAR WEATHER. ONCE THE PILOT WAS ABLE TO IDENTIFY HIS LOCATION HE ELECTED TO MAKE A GEAR UP LANDING AT THE NEAREST AIRPORT. METALLURGICAL EXAMINATION OF THE SEPARATED BLADE REVEALED THAT THE SEPARATION OF THE BLADE WAS THE RESULT OF FATIGUE CRACKING THAT INITIATED FROM MULTIPLE SITES LOCATED AT CORROSION PITS IN THE BALANCING HOLE. IT WAS DETERMINED THAT THE CORROSION PITTING HAD NOT BEEN DETECTED DURING THE LAST OVERHAUL AND PROCEDURES TO SHOT PEEN AND PAINT THE BALANCING HOLE WERE NOT PERFORMED.

Quoted verbatim from the NTSB record.