Accident Mitsubishi MU-2B-35 N770MA,
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ASN Wikibase Occurrence # 387406
 
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Date:Thursday 24 August 2000
Time:02:15 LT
Type:Silhouette image of generic MU2 model; specific model in this crash may look slightly different    
Mitsubishi MU-2B-35
Owner/operator:International Business Acft
Registration: N770MA
MSN: 625
Year of manufacture:1974
Total airframe hrs:9001 hours
Engine model:Garrett TPE-331-6-252
Fatalities:Fatalities: 0 / Occupants: 2
Aircraft damage: Substantial
Category:Accident
Location:Corsicana, TX -   United States of America
Phase: En route
Nature:Unknown
Departure airport:Dallas, TX (KDAL)
Destination airport:Houston, TX (KHOU)
Investigating agency: NTSB
Confidence Rating: Accident investigation report completed and information captured
Narrative:
The twin-engine airplane was in cruise flight at 11,000 feet msl, when the pilot heard a loud bang and felt the airplane vibrate. The pilot shut down the right engine, feathered the propeller, and landed the airplane at an alternate airport. Examination of the right propeller revealed that one of its propeller blades separated approximately 8.5 inches from the hub. This blade was manufactured from 7076 aluminum alloy, which is referred to as a 'hard alloy.' Examination of the propeller blade's fracture surface revealed that it failed as a result of fatigue cracking, which originated from an area of intergranular corrosion. The propeller was overhauled 222 hours prior to the accident. According to the overhaul facility, they used a process of Alodining the blades for corrosion control, which is an approved method. According to the propeller manufacturer, the preferred method of corrosion control is anodizing due to its corrosion detection properties; however, it is a more expensive and time consuming corrosion control process. As a result of this accident, the propeller manufacturer issued a service bulletin indicating that 'hard alloy' blades should be removed from service due to their susceptibility to intergranular corrosion.

Probable Cause: the in-flight separation of the propeller blade, which resulted from intergranular corrosion and fatigue cracking.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: FTW00LA242
Status: Investigation completed
Duration: 10 months
Download report: Final report

Sources:

NTSB FTW00LA242

Location

Revision history:

Date/timeContributorUpdates
03-May-2024 08:35 ASN Update Bot Added

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