Pilot Debrief

DOUGLAS DC 9 83 near Dayton, OH — 2017-03-19

Final reportENG17IA017
Sign in to save
Date
2017-03-19
Location
Dayton, OH, USA
Airport
DAY
Aircraft
DOUGLAS DC 9 83
Registration
N881GA
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Approach

Probable cause

The probable cause of the No. 2 (right) engine fire was an uncontained generator failure. Deformed rotating generator components and/or metal fragments radially released by the generator severed the constant speed drive-to-oil cooler return line located adjacent to the generator and caused oil to spray onto hot generator and engine case surfaces that subsequently ignited.

NTSB narrative

The No. 2 engine fire was caused by the uncontained failure of the generator main rotor. Deformed generator rotating components and/or metal fragments radially released by the generator severed the constant speed drive (CSD)-to-oil cooler return line located adjacent to the generator. The severed line sprayed oil onto hot generator and engine case surfaces that subsequently ignited. The sections of the generator main rotor that remained intact and the metal fragments recovered from the generator case exhibited extensive thermal and impact damage that precluded material analysis. The operating history of the failed generator was not available and federal regulations do not require operators to maintain hour and cycle counts for non-life limited components. An estimate of generator operating hours was provided by Allegiant Air and the date of manufacture was provided by UTC Aerospace Systems. Based on the available records the generator main rotor was never overhauled or re-wound and the total operating hours likely exceeded the 40,000 hour recommended overhaul interval specified in UTC Aerospace Systems service information letter (SIL) 449.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Performing maintenance checks on the No. 2 engine before the flight.

NTSB coding

  • Powerplant sys/comp malf/fail · Approach

Evidence available

  • 1 docket document
View NTSB final reportView NTSB docket

Docket documents1

Related mishaps