A saab 340B in cruise at 17000 ft declared an emergency and diverted due to failure of the left dc g...

Narrative:

While cruising at 17000 ft MSL, air carrier flight xyz from evv to dtw experienced master caution annunciator in conjunction with an overheat of the left dc generator. Performed emergency checklist. As instructed, we shut down left dc generator. Left dc generator light illuminated indicating generator was disconnected. Overtemp light extinguished after 2 mins indicating to crew that overheat condition had been resolved. Maintenance control was notified of situation. We both agreed (along with company) that flight could continue to destination safely as VMC conditions prevailed along our route of flight and dtw. Approximately 10 mins later, left dc generator light re- illuminated. Dispatch was notified that flight was diverting to indianapolis, in. This was at the discretion of the PIC and the flight crew as a whole to divert to indianapolis. This was based upon the fact that there were no more procedures to be followed. Notified ZAU of situation and declared an emergency. Simultaneously, left engine began to vibrate with associated variations in torque indications. We decided to keep engine running as all other indications (oil PPP, torque, itt, ng) were relatively stable and engine was producing power. Flight proceeded into indianapolis, in, without event. Fire trucks were present as aircraft rolled out on runway 23R. We believe this problem arose due to the fact that the generator drive shaft located on the ng (compressor) shaft accessory section had failed and not completely sheared away. Callback conversation with reporter revealed the following information: the reporter stated that when the master caution light and the generator overheat light came on, the generator was switched off with no immediate problem and we continued on as scheduled. The reporter said when the overheat light came on again it was associated with an abnormal engine vibration and the decision was made to divert. The reporter said when maintenance started work it was discovered the generator was coming apart and there was evidence of deicing fluid on the internal parts of the unit. The reporter said the reporter has knowledge of at least 3 other dc generator failures on this type aircraft and one of which came apart in the same manner.

Original NASA ASRS Text

Title: A SAAB 340B IN CRUISE AT 17000 FT DECLARED AN EMER AND DIVERTED DUE TO FAILURE OF THE L DC GENERATOR AND SUBSEQUENT OVERHEAT WARNING LIGHT AND ENG VIBRATIONS.

Narrative: WHILE CRUISING AT 17000 FT MSL, ACR FLT XYZ FROM EVV TO DTW EXPERIENCED MASTER CAUTION ANNUNCIATOR IN CONJUNCTION WITH AN OVERHEAT OF THE L DC GENERATOR. PERFORMED EMER CHKLIST. AS INSTRUCTED, WE SHUT DOWN L DC GENERATOR. L DC GENERATOR LIGHT ILLUMINATED INDICATING GENERATOR WAS DISCONNECTED. OVERTEMP LIGHT EXTINGUISHED AFTER 2 MINS INDICATING TO CREW THAT OVERHEAT CONDITION HAD BEEN RESOLVED. MAINT CTL WAS NOTIFIED OF SIT. WE BOTH AGREED (ALONG WITH COMPANY) THAT FLT COULD CONTINUE TO DEST SAFELY AS VMC CONDITIONS PREVAILED ALONG OUR RTE OF FLT AND DTW. APPROX 10 MINS LATER, L DC GENERATOR LIGHT RE- ILLUMINATED. DISPATCH WAS NOTIFIED THAT FLT WAS DIVERTING TO INDIANAPOLIS, IN. THIS WAS AT THE DISCRETION OF THE PIC AND THE FLC AS A WHOLE TO DIVERT TO INDIANAPOLIS. THIS WAS BASED UPON THE FACT THAT THERE WERE NO MORE PROCS TO BE FOLLOWED. NOTIFIED ZAU OF SIT AND DECLARED AN EMER. SIMULTANEOUSLY, L ENG BEGAN TO VIBRATE WITH ASSOCIATED VARIATIONS IN TORQUE INDICATIONS. WE DECIDED TO KEEP ENG RUNNING AS ALL OTHER INDICATIONS (OIL PPP, TORQUE, ITT, NG) WERE RELATIVELY STABLE AND ENG WAS PRODUCING PWR. FLT PROCEEDED INTO INDIANAPOLIS, IN, WITHOUT EVENT. FIRE TRUCKS WERE PRESENT AS ACFT ROLLED OUT ON RWY 23R. WE BELIEVE THIS PROB AROSE DUE TO THE FACT THAT THE GENERATOR DRIVE SHAFT LOCATED ON THE NG (COMPRESSOR) SHAFT ACCESSORY SECTION HAD FAILED AND NOT COMPLETELY SHEARED AWAY. CALLBACK CONVERSATION WITH RPTR REVEALED THE FOLLOWING INFO: THE RPTR STATED THAT WHEN THE MASTER CAUTION LIGHT AND THE GENERATOR OVERHEAT LIGHT CAME ON, THE GENERATOR WAS SWITCHED OFF WITH NO IMMEDIATE PROB AND WE CONTINUED ON AS SCHEDULED. THE RPTR SAID WHEN THE OVERHEAT LIGHT CAME ON AGAIN IT WAS ASSOCIATED WITH AN ABNORMAL ENG VIBRATION AND THE DECISION WAS MADE TO DIVERT. THE RPTR SAID WHEN MAINT STARTED WORK IT WAS DISCOVERED THE GENERATOR WAS COMING APART AND THERE WAS EVIDENCE OF DEICING FLUID ON THE INTERNAL PARTS OF THE UNIT. THE RPTR SAID THE RPTR HAS KNOWLEDGE OF AT LEAST 3 OTHER DC GENERATOR FAILURES ON THIS TYPE ACFT AND ONE OF WHICH CAME APART IN THE SAME MANNER.

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.

Attributes
ACN	426609
Time
Date	199901
Day	Mon
Local Time Of Day	1201 To 1800
Place
Locale Reference	atc facility : vhp
State Reference	IN
Altitude	msl bound lower : 17000 msl bound upper : 17000
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	SF 340B
Operating Under FAR Part	Part 135
Flight Phase	cruise other other other
Route In Use	enroute : on vectors enroute airway : v11
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : commercial
Experience	flight time last 90 days : 150 flight time total : 4000 flight time type : 500
ASRS Report	426609
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial
Events
Anomaly	aircraft equipment problem : critical
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : declared emergency other
Consequence	Other

A saab 340B in cruise at 17000 ft declared an emergency and diverted due to failure of the left dc generator and subsequent overheat warning light and engine vibrations.