Mechanic commentary on poor procedure for repair of exhaust duct adapter nuts. Not safety wired.

Attributes
ACN	271327
Time
Date	199405
Day	Wed
Local Time Of Day	1801 To 2400
Place
Locale Reference	airport : dtw
State Reference	MI
Altitude	agl bound lower : 0 agl bound upper : 0
Aircraft 1
Controlling Facilities	artcc : zbw
Operator	common carrier : air carrier
Make Model Name	Dash 8-100
Operating Under FAR Part	Part 135
Flight Phase	ground other : taxi
Person 1
Affiliation	company : air carrier
Function	other personnel other
Qualification	other other : other
ASRS Report	271327
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	aircraft equipment other aircraft equipment : unspecified other other : unspecified
Resolutory Action	other
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

During taxi out to the runway airlines flight dhc-8-100 got an engine fire warning on #2 engine. Engines were shut down, and the fire extinguisher was shot to the #2 engine and the fire warning went out. On inspection of the aircraft, it was found that the right hand exhaust duct was loose from the engine adapter. The engine exhaust adapter nut was backed out. The nut locking characteristic was not working. The nut could be tightened down by finger. On dash-8 aircraft the exhaust adapter nuts are not saftied. It's not required and it does not require replacement of the nut after it is removed. All it requires is that it is torqued. The adapter was removed and reinstalled on may/94 due to engine change. The engine exhaust duct should be saftied to prevent the nut from backing out and all nuts should be replaced, even if it looks like the lock in characteristics are good. The exhaust duct adapter was replaced and the aircraft was returned to service.

Original NASA ASRS Text

Title: MECH COMMENTARY ON POOR PROC FOR REPAIR OF EXHAUST DUCT ADAPTER NUTS. NOT SAFETY WIRED.

Narrative: DURING TAXI OUT TO THE RWY AIRLINES FLT DHC-8-100 GOT AN ENG FIRE WARNING ON #2 ENG. ENGS WERE SHUT DOWN, AND THE FIRE EXTINGUISHER WAS SHOT TO THE #2 ENG AND THE FIRE WARNING WENT OUT. ON INSPECTION OF THE ACFT, IT WAS FOUND THAT THE R HAND EXHAUST DUCT WAS LOOSE FROM THE ENG ADAPTER. THE ENG EXHAUST ADAPTER NUT WAS BACKED OUT. THE NUT LOCKING CHARACTERISTIC WAS NOT WORKING. THE NUT COULD BE TIGHTENED DOWN BY FINGER. ON DASH-8 ACFT THE EXHAUST ADAPTER NUTS ARE NOT SAFTIED. IT'S NOT REQUIRED AND IT DOES NOT REQUIRE REPLACEMENT OF THE NUT AFTER IT IS REMOVED. ALL IT REQUIRES IS THAT IT IS TORQUED. THE ADAPTER WAS REMOVED AND REINSTALLED ON MAY/94 DUE TO ENG CHANGE. THE ENG EXHAUST DUCT SHOULD BE SAFTIED TO PREVENT THE NUT FROM BACKING OUT AND ALL NUTS SHOULD BE REPLACED, EVEN IF IT LOOKS LIKE THE LOCK IN CHARACTERISTICS ARE GOOD. THE EXHAUST DUCT ADAPTER WAS REPLACED AND THE ACFT WAS RETURNED TO SVC.

Data retrieved from NASA's ASRS site as of July 2007 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.