Narrative:

Medium large transport dispatched with APU and power management computer (pmc) inoperative, 1+20 ATC hold at gate for local WX conditions. Upon reaching runway 35L holding area further delay for tailwind in excess of 10 KTS. Wind shifts to 260/15 and we are cleared for takeoff. Because aircraft is near maximum runway cross weight, a 'bleeds off' maximum power takeoff is required. Automatic throttles are engaged by the copilot who is making the takeoff. Before he calls for 'check maximum power' the master caution illuminates. I determine that the left engine bleed air has tripped (it has previously been turned off for takeoff). I advise the copilot to continue the takeoff. I then return attention to the engines and note the #2 N1 gauge red light is illuminated indicating an overspd condition. I reduce power on the #2 engine to the takeoff maximum power setting. The takeoff was continued and the aircraft performed normally the rest of the flight. Contributing factors were the inoperative systems on the aircraft, the WX related delays, strong crosswind and 2 different abnormals at the same time. The master caution worked properly in alerting us to the bleed trip indicated on the overhead panel. The red indicator lights on the N1, egt, N2 gauges proved very valuable because of first indicating an overspd on N1 and second for showing there was not an overtemp or overspd on N2. Because power was reduced quickly, there was no time to note actual engine reading of egt and N2. Also the digital readout on the gauges allowed quick reading of the N1 gauge. For maintenance purposes a memory recall of the peak N1, N2, egt and length of time at peak would help. Callback conversation with reporter revealed the following: further investigation revealed that the overspd warning came on at a relatively high speed during the takeoff run making an abort a very unattractive alternative. After departure the situation was discussed with air carrier maintenance and the decision was made to continue to destination. An apparently well handled potentially very dangerous occurrence.

Google
 

Original NASA ASRS Text

Title: ENGINE OVERSPEED WARNING CAME ON DURING TKOF ROLL. TKOF CONTINUED THRUST REDUCED TO MAXIMUM TKOF RPM ENGINE OPERATED NORMALLY FOR REMAINDER OF FLT.

Narrative: MLG DISPATCHED WITH APU AND POWER MGMNT COMPUTER (PMC) INOPERATIVE, 1+20 ATC HOLD AT GATE FOR LCL WX CONDITIONS. UPON REACHING RWY 35L HOLDING AREA FURTHER DELAY FOR TAILWIND IN EXCESS OF 10 KTS. WIND SHIFTS TO 260/15 AND WE ARE CLRED FOR TKOF. BECAUSE ACFT IS NEAR MAX RWY CROSS WEIGHT, A 'BLEEDS OFF' MAX POWER TKOF IS REQUIRED. AUTO THROTTLES ARE ENGAGED BY THE COPLT WHO IS MAKING THE TKOF. BEFORE HE CALLS FOR 'CHECK MAX POWER' THE MASTER CAUTION ILLUMINATES. I DETERMINE THAT THE LEFT ENGINE BLEED AIR HAS TRIPPED (IT HAS PREVIOUSLY BEEN TURNED OFF FOR TKOF). I ADVISE THE COPLT TO CONTINUE THE TKOF. I THEN RETURN ATTN TO THE ENGINES AND NOTE THE #2 N1 GAUGE RED LIGHT IS ILLUMINATED INDICATING AN OVERSPD CONDITION. I REDUCE POWER ON THE #2 ENGINE TO THE TKOF MAX POWER SETTING. THE TKOF WAS CONTINUED AND THE ACFT PERFORMED NORMALLY THE REST OF THE FLT. CONTRIBUTING FACTORS WERE THE INOPERATIVE SYSTEMS ON THE ACFT, THE WX RELATED DELAYS, STRONG XWIND AND 2 DIFFERENT ABNORMALS AT THE SAME TIME. THE MASTER CAUTION WORKED PROPERLY IN ALERTING US TO THE BLEED TRIP INDICATED ON THE OVERHEAD PANEL. THE RED INDICATOR LIGHTS ON THE N1, EGT, N2 GAUGES PROVED VERY VALUABLE BECAUSE OF FIRST INDICATING AN OVERSPD ON N1 AND SECOND FOR SHOWING THERE WAS NOT AN OVERTEMP OR OVERSPD ON N2. BECAUSE POWER WAS REDUCED QUICKLY, THERE WAS NO TIME TO NOTE ACTUAL ENGINE READING OF EGT AND N2. ALSO THE DIGITAL READOUT ON THE GAUGES ALLOWED QUICK READING OF THE N1 GAUGE. FOR MAINT PURPOSES A MEMORY RECALL OF THE PEAK N1, N2, EGT AND LENGTH OF TIME AT PEAK WOULD HELP. CALLBACK CONVERSATION WITH REPORTER REVEALED THE FOLLOWING: FURTHER INVESTIGATION REVEALED THAT THE OVERSPD WARNING CAME ON AT A RELATIVELY HIGH SPEED DURING THE TKOF RUN MAKING AN ABORT A VERY UNATTRACTIVE ALTERNATIVE. AFTER DEP THE SITUATION WAS DISCUSSED WITH ACR MAINT AND THE DECISION WAS MADE TO CONTINUE TO DEST. AN APPARENTLY WELL HANDLED POTENTIALLY VERY DANGEROUS OCCURRENCE.

Data retrieved from NASA's ASRS site as of August 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.