Narrative:

APU was inoperative. Started left engine at gate. ZZZ procedures call for xbleed start in alley. We pushed back from az. As we were towed forward, the ground man advised cleared to start engine #2. Since I have done very few xbleed starts, I had reviewed the procedure earlier at the gate, but I had never considered doing it while being towed. I thought since the ramp alley looked bare and dry and as long as I guarded the brakes it would be safe. I was wrong. I did not notice some glycol at spot Y. Just after I reduced the left engine to idle, the ground man called brakes. I immediately stopped the aircraft. The tug jackknifed and the tow bar bent. I called out maintenance to inspect the nose gear. There was no damage to the aircraft. Afterwards, I asked the tug driver if it was normal to xbleed start during the tow and he said yes. I think that I was wrong to use more than idle power while being towed and I will never do it again. I will wait until the tug is disconnected before doing a xbleed start and be more cautious for glycol or anything that might preclude even doing a normal engine start during tow. I think that there should be more guidance in the aircraft flight manual regarding xbleed starts. I am really concerned about what could have happened to the tug driver had I not stopped as quick as I did.

Related reports:

Google
 

Original NASA ASRS Text

Title: AN MD SUPER 80 BEING TOWED FROM THE GATE TO THE TXWY WITH THE APU INOP AND THE L ENG RUNNING MAKES A XBLEED START OF #2 ENG. JUST AFTER REDUCING PWR ON #1 ENG THE TUG STOPPED INCURRING DAMAGE TO THE TOW BAR.

Narrative: APU WAS INOP. STARTED L ENG AT GATE. ZZZ PROCS CALL FOR XBLEED START IN ALLEY. WE PUSHED BACK FROM AZ. AS WE WERE TOWED FORWARD, THE GND MAN ADVISED CLRED TO START ENG #2. SINCE I HAVE DONE VERY FEW XBLEED STARTS, I HAD REVIEWED THE PROC EARLIER AT THE GATE, BUT I HAD NEVER CONSIDERED DOING IT WHILE BEING TOWED. I THOUGHT SINCE THE RAMP ALLEY LOOKED BARE AND DRY AND AS LONG AS I GUARDED THE BRAKES IT WOULD BE SAFE. I WAS WRONG. I DID NOT NOTICE SOME GLYCOL AT SPOT Y. JUST AFTER I REDUCED THE L ENG TO IDLE, THE GND MAN CALLED BRAKES. I IMMEDIATELY STOPPED THE ACFT. THE TUG JACKKNIFED AND THE TOW BAR BENT. I CALLED OUT MAINT TO INSPECT THE NOSE GEAR. THERE WAS NO DAMAGE TO THE ACFT. AFTERWARDS, I ASKED THE TUG DRIVER IF IT WAS NORMAL TO XBLEED START DURING THE TOW AND HE SAID YES. I THINK THAT I WAS WRONG TO USE MORE THAN IDLE PWR WHILE BEING TOWED AND I WILL NEVER DO IT AGAIN. I WILL WAIT UNTIL THE TUG IS DISCONNECTED BEFORE DOING A XBLEED START AND BE MORE CAUTIOUS FOR GLYCOL OR ANYTHING THAT MIGHT PRECLUDE EVEN DOING A NORMAL ENG START DURING TOW. I THINK THAT THERE SHOULD BE MORE GUIDANCE IN THE ACFT FLT MANUAL REGARDING XBLEED STARTS. I AM REALLY CONCERNED ABOUT WHAT COULD HAVE HAPPENED TO THE TUG DRIVER HAD I NOT STOPPED AS QUICK AS I DID.

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.