A widebody transport tow bar was bent when an engine accelerated past ground idle on start.

Attributes
ACN	265880
Time
Date	199403
Day	Sat
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : ewr
State Reference	NJ
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	common carrier : air carrier
Make Model Name	Commercial Fixed Wing
Operating Under FAR Part	Part 121
Navigation In Use	Other
Flight Phase	other
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Experience	flight time last 90 days : 160 flight time total : 16000 flight time type : 3500
ASRS Report	265880
Person 2
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : atp
Experience	flight time last 90 days : 250 flight time total : 7500 flight time type : 3500
ASRS Report	265726
Events
Anomaly	aircraft equipment problem : critical other anomaly other anomaly other
Independent Detector	other flight crewa other other : unspecified
Resolutory Action	none taken : detected after the fact
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	other

Narrative:

During tow out we were cleared to start engine #2. As the engine was starting, I heard a popping sound like a circuit breaker popping. I said 'I heard something pop.' I kept monitoring the engine start. I then noticed that the engine was accelerating through ground idle. It kept accelerating. I immediately placed the start lever to the cutoff position to shut down the engine. Due to the thrust of the engine, the nose of the aircraft was pushed to the left and the tow bar was damaged. All procedures and checklists were completed and at no time were the thrust levers out of idle. I recommend that the engines be started with the brakes set. Supplemental information from acn 265726: I took a quick look back to see if a breaker had really popped and I heard #2 engine accelerate. I immediately applied full force on the brakes and grabbed the throttles, which were in the idle position. The captain shut the fuel lever off.

Original NASA ASRS Text

Title: A WDB TOW BAR WAS BENT WHEN AN ENG ACCELERATED PAST GND IDLE ON START.

Narrative: DURING TOW OUT WE WERE CLRED TO START ENG #2. AS THE ENG WAS STARTING, I HEARD A POPPING SOUND LIKE A CIRCUIT BREAKER POPPING. I SAID 'I HEARD SOMETHING POP.' I KEPT MONITORING THE ENG START. I THEN NOTICED THAT THE ENG WAS ACCELERATING THROUGH GND IDLE. IT KEPT ACCELERATING. I IMMEDIATELY PLACED THE START LEVER TO THE CUTOFF POS TO SHUT DOWN THE ENG. DUE TO THE THRUST OF THE ENG, THE NOSE OF THE ACFT WAS PUSHED TO THE L AND THE TOW BAR WAS DAMAGED. ALL PROCS AND CHKLISTS WERE COMPLETED AND AT NO TIME WERE THE THRUST LEVERS OUT OF IDLE. I RECOMMEND THAT THE ENGS BE STARTED WITH THE BRAKES SET. SUPPLEMENTAL INFORMATION FROM ACN 265726: I TOOK A QUICK LOOK BACK TO SEE IF A BREAKER HAD REALLY POPPED AND I HEARD #2 ENG ACCELERATE. I IMMEDIATELY APPLIED FULL FORCE ON THE BRAKES AND GRABBED THE THROTTLES, WHICH WERE IN THE IDLE POS. THE CAPT SHUT THE FUEL LEVER OFF.

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.