Air carrier flight crew operated malfunctioned APU aircraft equipment even though the APU had been w...

Attributes
ACN	203644
Time
Date	199203
Day	Wed
Local Time Of Day	0601 To 1200
Place
Locale Reference	airport : lga
State Reference	NY
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	Medium Large Transport, Low Wing, 2 Turbojet Eng
Flight Phase	ground other : taxi
Flight Plan	IFR
Person 1
Affiliation	company : air carrier
Function	flight crew : first officer
Qualification	pilot : commercial pilot : flight engineer pilot : instrument pilot : atp
Experience	flight time last 90 days : 202 flight time total : 10000 flight time type : 4356
ASRS Report	203644
Person 2
Affiliation	company : air carrier
Function	flight crew : captain oversight : pic
Qualification	pilot : atp
Events
Anomaly	aircraft equipment problem : critical non adherence : far non adherence other other anomaly other
Independent Detector	aircraft equipment other aircraft equipment : unspecified other flight crewa
Resolutory Action	flight crew : overcame equipment problem
Consequence	Other
Supplementary
Primary Problem	Aircraft
Air Traffic Incident	Pilot Deviation

Narrative:

The aircraft we were using today had an MEL on the APU for its having previously pumped smoke into the cabin. Although the logbook write-up that prompted its being taken OTS did not say so specifically, the captain assumed that the actual problem was one wherein the smoke had been created only when using the APU air source for air conditioning on the ground, and not merely from running the APU and pumping exhaust fumes inside. The captain, therefore, directed that the APU be started and used for engine start. Subsequent to starting 1 engine and taxiing out with the other one still shut down, so as to save fuel, I reverted to old usual habits and turned on the left air conditioning pack using air from the now-running left engine and the right pack using the air from the APU. Clearly, this should not have been done since 3 or 4 mins afterward, the aft flight attendant came forward to advise that there was smoke coming into the cabin and both lavatory smoke detectors were sounding. Immediately, I turned off the right air conditioning pack to eliminate the smoke source. We next started the right engine and used its air to clear out the smoke as rapidly as possible. As to cause, it's clear the primary one is my failure to remember not to use the APU as a source of air and turning on the right air conditioning pack after starting only the left engine. Contributing also I believe, was the captain's deviating from MEL procedures by using the APU when it was not necessary, and should have been left off to begin with. Unfortunately, this was just one more of the instances during this 3 day trip when this captain deviated from recommended or regulated procedure. In this case, I was caught compounding the deviation by doing just what the 'totally inoperative' nature of the MEL procedures tried to avoid. I feel the first corrective action would be to follow procedures in all instances. Had we complied with the MEL, and left the APU off to begin with, there never would have been a chance for this problem occurring.

Original NASA ASRS Text

Title: ACR FLC OPERATED MALFUNCTIONED APU ACFT EQUIP EVEN THOUGH THE APU HAD BEEN WRITTEN-UP IN THE ACFT RECORDS AS OTS DUE TO CAUSING SMOKE IN THE PAX CABIN.

Narrative: THE ACFT WE WERE USING TODAY HAD AN MEL ON THE APU FOR ITS HAVING PREVIOUSLY PUMPED SMOKE INTO THE CABIN. ALTHOUGH THE LOGBOOK WRITE-UP THAT PROMPTED ITS BEING TAKEN OTS DID NOT SAY SO SPECIFICALLY, THE CAPT ASSUMED THAT THE ACTUAL PROBLEM WAS ONE WHEREIN THE SMOKE HAD BEEN CREATED ONLY WHEN USING THE APU AIR SOURCE FOR AIR CONDITIONING ON THE GND, AND NOT MERELY FROM RUNNING THE APU AND PUMPING EXHAUST FUMES INSIDE. THE CAPT, THEREFORE, DIRECTED THAT THE APU BE STARTED AND USED FOR ENG START. SUBSEQUENT TO STARTING 1 ENG AND TAXIING OUT WITH THE OTHER ONE STILL SHUT DOWN, SO AS TO SAVE FUEL, I REVERTED TO OLD USUAL HABITS AND TURNED ON THE L AIR CONDITIONING PACK USING AIR FROM THE NOW-RUNNING L ENG AND THE R PACK USING THE AIR FROM THE APU. CLRLY, THIS SHOULD NOT HAVE BEEN DONE SINCE 3 OR 4 MINS AFTERWARD, THE AFT FLT ATTENDANT CAME FORWARD TO ADVISE THAT THERE WAS SMOKE COMING INTO THE CABIN AND BOTH LAVATORY SMOKE DETECTORS WERE SOUNDING. IMMEDIATELY, I TURNED OFF THE R AIR CONDITIONING PACK TO ELIMINATE THE SMOKE SOURCE. WE NEXT STARTED THE R ENG AND USED ITS AIR TO CLR OUT THE SMOKE AS RAPIDLY AS POSSIBLE. AS TO CAUSE, IT'S CLR THE PRIMARY ONE IS MY FAILURE TO REMEMBER NOT TO USE THE APU AS A SOURCE OF AIR AND TURNING ON THE R AIR CONDITIONING PACK AFTER STARTING ONLY THE L ENG. CONTRIBUTING ALSO I BELIEVE, WAS THE CAPT'S DEVIATING FROM MEL PROCS BY USING THE APU WHEN IT WAS NOT NECESSARY, AND SHOULD HAVE BEEN L OFF TO BEGIN WITH. UNFORTUNATELY, THIS WAS JUST ONE MORE OF THE INSTANCES DURING THIS 3 DAY TRIP WHEN THIS CAPT DEVIATED FROM RECOMMENDED OR REGULATED PROC. IN THIS CASE, I WAS CAUGHT COMPOUNDING THE DEV BY DOING JUST WHAT THE 'TOTALLY INOP' NATURE OF THE MEL PROCS TRIED TO AVOID. I FEEL THE FIRST CORRECTIVE ACTION WOULD BE TO FOLLOW PROCS IN ALL INSTANCES. HAD WE COMPLIED WITH THE MEL, AND L THE APU OFF TO BEGIN WITH, THERE NEVER WOULD HAVE BEEN A CHANCE FOR THIS PROBLEM OCCURRING.

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.

Air carrier flight crew operated malfunctioned APU aircraft equipment even though the APU had been written-up in the aircraft records as OTS due to causing smoke in the passenger cabin.