Airbus Industrie Undifferentiated or Other Model
Maintenance Airframe; Maintenance Avionics; Maintenance Powerplant
Troubleshooting; Time Pressure; Situational Awareness; Distraction; Workload
Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
General Flight Cancelled / Delayed
Aircraft; Company Policy; Environment - Non Weather Related; Human Factors; Logbook Entry; Procedure
I was dispatched to an Airbus aircraft to respond to a crew call just prior to aircraft departure. The information I was given at the time was that the 'DFDR OFF' light would not illuminate with the aircraft on the ground. In other words; it was failing the Preflight Test. After some discussion with the flight crew they finally revealed that there were some other anomalies with the aircraft. Chief among these anomalies was that the Windshear Alert would not test properly. I asked the flight crew to write-up the discrepancy in the logbook and I would begin to troubleshoot. They made their entry but already being aware of the problems on the aircraft; I only glanced at the write-up and immediately began troubleshooting. At this time; I had also begun formulating an idea that the problems on the aircraft were most likely traceable to a single source - not multiple independent failures.I was quite sure at that point that the aircraft 'thought' it was in a phase of flight other than being parked with engines off. The main suspect in my mind was that one of the engine oil pressure switches was stuck in a position that showed oil pressure - thus triggering a chain of events within the aircraft to make it 'think' that one of the engines was running. At that point; I decided to go back to my 'Line Shack' [Maintenance office] in order to verify this hypothesis via the Maintenance Manuals; wiring diagrams; etc... After reviewing the necessary information in the manuals; I had confirmed to myself that a faulty Oil Pressure Switch (or the wiring related to it) could cause the problem. During this time; I had also researched the Part Number for a new oil pressure switch; gave the part number to my Lead Technician and asked him to order it for me while I headed back out to the airplane. Line Maintenance; apparently hearing over the radio that there may be an oil pressure problem; had gone out to the airplane while I was inside and reported that the # 2 Engine appeared to be the one with the oil pressure problem. By the time I got out to the airplane; the # 2 Engine cowlings were just getting opened and I immediately located the # 2 Engine Oil Pressure Switch.As I began looking at the oil pressure switch; my Lead Technician informed me that we had no oil pressure switches in stock and to let him know as soon as possible if the airplane would need to be transloaded. Reviewing the wiring diagrams; I knew that in order for the aircraft to sense an engine NOT running; the engine oil pressure switch would have to make contact with a ground connection. When I disconnected the Cannon plug; I immediately noticed what appeared to be a small piece of an unknown substance (it had the consistency and texture of rubber); clogged in Pin 'C' of the Cannon plug and I also noticed what I presumed was a slight coating of what appeared to be oil on the surface of the Cannon plug. I was able to extract the piece of rubber and I was also able to clean the Cannon plug per the Airbus Electrical Standard Practices Manual (ESPM).Further inspection of the connector and oil pressure switch revealed no abnormalities that I could detect in terms of where the debris came from. It appeared to have come from a source external to the switch and the Cannon plug. At that point; I decided to 'jumper' pins 'B' and 'C' to each other to see if the indications in the cockpit worked. It was reported to me by Line Maintenance who offered to check; that the [flight] crew said everything was working. At that point; I disconnected the jumper wire; reconnected the Cannon plug and went upstairs to make sure all of the indications were normal. Again; they were normal. Just to be on the safe side and to ensure that it was a 'good fix' I asked the [flight] crew to start the # 2 Engine just to ensure a clean transition from a low oil pressure indication; the eradication of the low oil pressure indication when oil pressure began to rise and back to a low oil pressure indication when oil pressure dropped of everything worked as it was supposed to. I then began to perform the Operational Checkouts of the systems that I was initially called for ('DFDR OFF' light and Windshear Alerts inoperative) per the applicable Maintenance Manuals (M/Ms); as I suspected; and with no great surprise; they all checked out. As I was finishing the last of these checks; either the flight crew informed me; or my Lead called me (I can't remember which) to let me know that they were calling the airplane down and were going to transfer the freight to another aircraft. Knowing the plane was nearly an hour past departure; the flight crew looked at me and I told them the only thing left was paperwork. I also remember calling my Lead and informing him not to make that call; as the plane was fixed and I just needed to perform the necessary paperwork. I immediately began upon the task of trying to recount everything that had taken place in the last hour while feeling very pressed for time. The key thing in my mind at the time was the oil pressure switch (and its Cannon plug) and how through various methods I had confirmed that the debris in the Cannon plug appeared to be the culprit. I suppose that this led me to overlook the precise wording of what the flight crew had written up as I began my sign-off. I had a large number of Maintenance Manuals; wiring diagrams and other references in the cockpit. I tried to be as quick but as informative as possible in my sign off; and again; I was more focused on the root cause of all the anomalies than I was on each individual anomaly. Thus; I entered what I felt were the most descriptive manuals regarding the maintenance actions that I had performed. That the wiring diagrams showed how the system operated electrically; the disconnecting and reconnecting of the Cannon plugs via the ESPM; and the removal and installation (of which the full procedure was not necessary to do) of the low oil pressure switch were more than sufficient for anyone looking into this particular maintenance event to plainly see the steps taken; why the Cannon plug caused the problem; and how it affected the overall operation of other aircraft systems. However; in my haste; I don't think I noticed the particular way in which the flight crew had written up the discrepancy. I was more focused on the part of the write-up that said 'Flt Data Recorder operates as though engines running...' because that was indeed the case. After I had signed the logbook; I handed it to the flight crew to look over and he even complimented me on the thoroughness of the paperwork. Having that secondary confirmation; I assumed all was well; the necessary aircraft systems were functional; and I departed the aircraft. I believe that several factors occurred which are leading me to write this statement. The nature of the maintenance call being a 'block out' (a call just prior to departure) was chief among them in that it automatically put a great sense of urgency on the situation. This was compounded by the fact that I had to retrieve a large number of Maintenance Manuals; troubleshoot; and perform whatever steps necessary to successfully and properly fix the aircraft - but all of these tasks take time. Because of the urgency this atmosphere created; and because I felt I was familiar enough with the problems on the aircraft; I suspect I did not take the time to properly read the logbook entry. Not to mention; the logbook entry; if we are to be technical; had more than one discrepancy in it ('DFDR OFF' light and Windshear Alert). What I assume is the psychological impact of having one logbook sheet; perhaps creates an environment and perhaps a false mentality that there was only one problem on the aircraft and that only one single thing needed to be addressed in the sign-off. Upon signing the aircraft logbook off; I was further hastened by the awareness that they were going to transload the aircraft despite me having finished what I feltwere all necessary maintenance activities. I assume it was at that point that I felt I really needed to hurry with the paperwork. There is not much that can be done in aviation to prevent calls prior to departure. There will; I presume; always be a certain sense of urgency. This is not to say that oversights are excusable due to a sense of urgency; but that we (as Airmen) must always be cognizant of what our limitations are in the face of that sense of urgency and to be aware that; that is when oversights are most likely to occur. In no way do I blame the flight crew for the situation; but it would perhaps be much better for all of us if multiple discrepancies (even if they may seem related) are written on separate log sheets. This would greatly prevent situations like this from happening as each individual problem would need to be addressed rather than creating what I consider a 'false mentality' of 'One logsheet; One problem.' I do take certain issues with various personnel (lead technicians; load crews; managers; etc...) asking about the status of an airplane while in the middle of an 'urgent situation.' If a lead technician calls a mechanic; chances are that the mechanic has been asked by the flight crew; a load crew; and several other people what the status of the aircraft is within a relatively short amount of time. This is all very distracting and happens on a consistent basis. It effectively turns the mechanic into a Call Center who has to answer to every single person while distracting from the ultimate goal: which is to provide safe and reliable aircraft. Finally; as a personal lesson; I will always be sure that every log sheet is read with utmost attention regardless of how much I think I am aware of the current situation.
Reporter stated the Engine Oil Pressure Switch feeds information to a number of other aircraft systems including the Hi-Low Speed positions for the Equipment Cooling Fan and display information for the Engine Fuel switches. He has twenty years aircraft maintenance experience that includes avionics training in the Military.
During preflight; I noticed that the Flight Data Recorder (FDR) switch would depress properly; but would not indicate 'ON'; as desired. I also noticed that the Aural Wind Shear Alert warning failed to sound. I called Maintenance. Two mechanics arrived to fix the problem; which they succeeded in doing after forty-five or so minutes work. I asked if I should put both items on the same write-up; or not. Since they seemed to be symptoms of the same problem the mechanics recommended that I include them on the same write-up. I now realize the error in not making two separate write-ups for the separate items. I could have mentioned the two items as seeming to be related to the same problem to facilitate the subsequent analysis for the mechanics; but should still make separate entries. [Recommend] making separate entries for all MEL items per the FOM.
Line Mechanic explains a logbook sign-off and the troubleshooting procedures he used to address a 'DFDR OFF' light that would not illuminate and a Windshear Alert Warning that would not test properly on an Airbus aircraft; at departure time. A pilot also reports he wrote-up both discrepancies on the same logbook sheet instead of two separate Log sheets.