Narrative:

Jul/xa/97, flight #1 (iah-las) and flight #2 (las-iah). Prior to flight #1, upon arrival at aircraft, I discovered a placard on the maintenance log which stated that the #2 oil filter bypass warning light was inoperative. I opened the MEL (system 79-2) and found that (M) 'one may be inoperative provided: a) malfunction is in the warning system, and B) main oil screen is inspected for presence of contaminants at least every 12 hours.' after looking through the log I came to the conclusion that there was no 'time' written down that would satisfy the 'every 12 hours' part of the MEL requirement. I immediately called maintenance over the radio to report this and they said that a mechanic would inspect the filter and make the 'time' entry in the log. The mechanic came to the cockpit and said they intended to 'fix' the indicator. After a period of time the mechanic came back to the cockpit, ran the #2 engine and removed the placard from the warning light. (Switch to las vegas.) prior to departure time of flight #2, in las, an FAA aci made his presence and jump seat intentions known to me. After pushback/disconnect and at the start of taxi out, our #2 oil filter bypass warning light illuminated for a brief period of time. Even though the light was no longer illuminated, we stopped our taxi and got into and went through the abnormal checklist. After the checklist, the 3 of us discussed the indication. Because of the 'history' of the indicating system and because the light had come on for such a short time and then had gone out, we came to the conclusion that a 'light on' was a malfunction in the warning system rather than an actual filter problem -- so we continued. After a lengthy taxi time (during which the light remained out) we were cleared into position for takeoff. As we turned onto the runway I told the first officer that if the light came on during the takeoff roll my course of action would be to continue the takeoff rather than reject. I understand that the FAA jump seater states that the light did illuminate during the takeoff roll(?) however, I honestly don't remember if it did or not.we continued a normal flight towards houston until just west of el paso, at which point we got another 'light.' we went through the abnormal checklist again and over a period of time discovered that in order to keep the light 'out' we had to have the #2 power lever progressively towards the idle position. I was now having second thoughts about the indicator -- that it might be the filter and that we might have to shut the engine down. We were at a very heavy weight (approximately 160000 pounds) and with an isa of approximately +15 degrees, it was becoming evident that we couldn't maintain cruise altitude with maximum continuous power on #1 and #3 with #2 pulled back to idle. The WX at lower altitudes between el paso and houston was questionable and we had austin as an alternate for houston. I discussed my concerns with the crew about the possibility of having to shut #2 engine down, the WX at lower cruising altitudes, and the slim possibility of having to divert to austin from houston -- with an engine shut down, and we agreed that the safest course of action was to divert into el paso, approximately 50 mi from our position and having good WX. We did divert to el paso. After a delay in el paso of approximately 4-5 hours, the contract maintenance man discovered our problem was, in fact, a faulty indicating system (as per its history) rather than a filter problem. A placard went back on the system and we were sent on our way to houston. By the way, sometime after our arrival in el paso, our FAA acm discovered that there was a B737 aircraft at another gate that was about to leave for houston and he chose to continue his flight on that aircraft rather than waiting for our release. I completed a captain's irregularity report and called the operations director in system control while in el paso. Supplemental information from acn 375184: we were cleared to take off in las vegas, with an FAA inspector in the jump seat. After doing the before takeoff checklist, I focused my attention on the flight engineer panel until 100 KTS, which is SOP. At about this time, I looked forward, and saw the oil filter bypass light was on. The FAA inspector called out that the light was on. Once in the air, as per the abnormal checklist, we retarded the throttle until the light went out, pushing the throttle all the way forward to climb power, the light remained out. The light stayed out until we neared el paso, at which time it came back on. We decided to make an unscheduled landing in el paso to have it checked. The filter was checked, and nothing was found wrong, and the oil filter bypass light was placarded inoperative, once again. We then proceeded routinely to houston, with the light illuminated and placarded.

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Original NASA ASRS Text

Title: AN ACR B727 FLC HAD THE #2 OIL FILTER BYPASS WARNING ILLUMINATE SEVERAL TIMES DURING A FLT AND EACH TIME THEY WERE ABLE TO EXTINGUISH THE LIGHT USING THE CHKLIST PROC, EXCEPT THAT DURING CRUISE THEY FOUND THAT THE LIGHT WOULD STAY OUT IF THE #2 ENG WAS OPERATED AT IDLE. THE FLC DECIDED TO DIVERT TO ELP WHERE THE WARNING SYS WAS FOUND TO BE FAULTY AND PLACARDED.

Narrative: JUL/XA/97, FLT #1 (IAH-LAS) AND FLT #2 (LAS-IAH). PRIOR TO FLT #1, UPON ARR AT ACFT, I DISCOVERED A PLACARD ON THE MAINT LOG WHICH STATED THAT THE #2 OIL FILTER BYPASS WARNING LIGHT WAS INOP. I OPENED THE MEL (SYS 79-2) AND FOUND THAT (M) 'ONE MAY BE INOP PROVIDED: A) MALFUNCTION IS IN THE WARNING SYS, AND B) MAIN OIL SCREEN IS INSPECTED FOR PRESENCE OF CONTAMINANTS AT LEAST EVERY 12 HRS.' AFTER LOOKING THROUGH THE LOG I CAME TO THE CONCLUSION THAT THERE WAS NO 'TIME' WRITTEN DOWN THAT WOULD SATISFY THE 'EVERY 12 HRS' PART OF THE MEL REQUIREMENT. I IMMEDIATELY CALLED MAINT OVER THE RADIO TO RPT THIS AND THEY SAID THAT A MECH WOULD INSPECT THE FILTER AND MAKE THE 'TIME' ENTRY IN THE LOG. THE MECH CAME TO THE COCKPIT AND SAID THEY INTENDED TO 'FIX' THE INDICATOR. AFTER A PERIOD OF TIME THE MECH CAME BACK TO THE COCKPIT, RAN THE #2 ENG AND REMOVED THE PLACARD FROM THE WARNING LIGHT. (SWITCH TO LAS VEGAS.) PRIOR TO DEP TIME OF FLT #2, IN LAS, AN FAA ACI MADE HIS PRESENCE AND JUMP SEAT INTENTIONS KNOWN TO ME. AFTER PUSHBACK/DISCONNECT AND AT THE START OF TAXI OUT, OUR #2 OIL FILTER BYPASS WARNING LIGHT ILLUMINATED FOR A BRIEF PERIOD OF TIME. EVEN THOUGH THE LIGHT WAS NO LONGER ILLUMINATED, WE STOPPED OUR TAXI AND GOT INTO AND WENT THROUGH THE ABNORMAL CHKLIST. AFTER THE CHKLIST, THE 3 OF US DISCUSSED THE INDICATION. BECAUSE OF THE 'HISTORY' OF THE INDICATING SYS AND BECAUSE THE LIGHT HAD COME ON FOR SUCH A SHORT TIME AND THEN HAD GONE OUT, WE CAME TO THE CONCLUSION THAT A 'LIGHT ON' WAS A MALFUNCTION IN THE WARNING SYS RATHER THAN AN ACTUAL FILTER PROB -- SO WE CONTINUED. AFTER A LENGTHY TAXI TIME (DURING WHICH THE LIGHT REMAINED OUT) WE WERE CLRED INTO POS FOR TKOF. AS WE TURNED ONTO THE RWY I TOLD THE FO THAT IF THE LIGHT CAME ON DURING THE TKOF ROLL MY COURSE OF ACTION WOULD BE TO CONTINUE THE TKOF RATHER THAN REJECT. I UNDERSTAND THAT THE FAA JUMP SEATER STATES THAT THE LIGHT DID ILLUMINATE DURING THE TKOF ROLL(?) HOWEVER, I HONESTLY DON'T REMEMBER IF IT DID OR NOT.WE CONTINUED A NORMAL FLT TOWARDS HOUSTON UNTIL JUST W OF EL PASO, AT WHICH POINT WE GOT ANOTHER 'LIGHT.' WE WENT THROUGH THE ABNORMAL CHKLIST AGAIN AND OVER A PERIOD OF TIME DISCOVERED THAT IN ORDER TO KEEP THE LIGHT 'OUT' WE HAD TO HAVE THE #2 PWR LEVER PROGRESSIVELY TOWARDS THE IDLE POS. I WAS NOW HAVING SECOND THOUGHTS ABOUT THE INDICATOR -- THAT IT MIGHT BE THE FILTER AND THAT WE MIGHT HAVE TO SHUT THE ENG DOWN. WE WERE AT A VERY HVY WT (APPROX 160000 LBS) AND WITH AN ISA OF APPROX +15 DEGS, IT WAS BECOMING EVIDENT THAT WE COULDN'T MAINTAIN CRUISE ALT WITH MAX CONTINUOUS PWR ON #1 AND #3 WITH #2 PULLED BACK TO IDLE. THE WX AT LOWER ALTS BTWN EL PASO AND HOUSTON WAS QUESTIONABLE AND WE HAD AUSTIN AS AN ALTERNATE FOR HOUSTON. I DISCUSSED MY CONCERNS WITH THE CREW ABOUT THE POSSIBILITY OF HAVING TO SHUT #2 ENG DOWN, THE WX AT LOWER CRUISING ALTS, AND THE SLIM POSSIBILITY OF HAVING TO DIVERT TO AUSTIN FROM HOUSTON -- WITH AN ENG SHUT DOWN, AND WE AGREED THAT THE SAFEST COURSE OF ACTION WAS TO DIVERT INTO EL PASO, APPROX 50 MI FROM OUR POS AND HAVING GOOD WX. WE DID DIVERT TO EL PASO. AFTER A DELAY IN EL PASO OF APPROX 4-5 HRS, THE CONTRACT MAINT MAN DISCOVERED OUR PROB WAS, IN FACT, A FAULTY INDICATING SYS (AS PER ITS HISTORY) RATHER THAN A FILTER PROB. A PLACARD WENT BACK ON THE SYS AND WE WERE SENT ON OUR WAY TO HOUSTON. BY THE WAY, SOMETIME AFTER OUR ARR IN EL PASO, OUR FAA ACM DISCOVERED THAT THERE WAS A B737 ACFT AT ANOTHER GATE THAT WAS ABOUT TO LEAVE FOR HOUSTON AND HE CHOSE TO CONTINUE HIS FLT ON THAT ACFT RATHER THAN WAITING FOR OUR RELEASE. I COMPLETED A CAPT'S IRREGULARITY RPT AND CALLED THE OPS DIRECTOR IN SYS CTL WHILE IN EL PASO. SUPPLEMENTAL INFO FROM ACN 375184: WE WERE CLRED TO TAKE OFF IN LAS VEGAS, WITH AN FAA INSPECTOR IN THE JUMP SEAT. AFTER DOING THE BEFORE TKOF CHKLIST, I FOCUSED MY ATTN ON THE FE PANEL UNTIL 100 KTS, WHICH IS SOP. AT ABOUT THIS TIME, I LOOKED FORWARD, AND SAW THE OIL FILTER BYPASS LIGHT WAS ON. THE FAA INSPECTOR CALLED OUT THAT THE LIGHT WAS ON. ONCE IN THE AIR, AS PER THE ABNORMAL CHKLIST, WE RETARDED THE THROTTLE UNTIL THE LIGHT WENT OUT, PUSHING THE THROTTLE ALL THE WAY FORWARD TO CLB PWR, THE LIGHT REMAINED OUT. THE LIGHT STAYED OUT UNTIL WE NEARED EL PASO, AT WHICH TIME IT CAME BACK ON. WE DECIDED TO MAKE AN UNSCHEDULED LNDG IN EL PASO TO HAVE IT CHKED. THE FILTER WAS CHKED, AND NOTHING WAS FOUND WRONG, AND THE OIL FILTER BYPASS LIGHT WAS PLACARDED INOP, ONCE AGAIN. WE THEN PROCEEDED ROUTINELY TO HOUSTON, WITH THE LIGHT ILLUMINATED AND PLACARDED.

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.