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Unserviceabilities with Unusual Symptoms ..

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Unserviceabilities with Unusual Symptoms ..

Old 23rd May 2009, 19:02
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Leak Measurement Vlvs

Seen Quite A Few A320, A330 And A340 Return To Stand Due Leak Measurement Vlv Left Engaged
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Old 15th Jun 2009, 00:16
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On ground HYD EDP selected to OFF to check on another matter, notice HYD system remains pressurised at 3,000PSI??? Re-cycle and check C.B, still remains pressurised.

Cause : The HYD EDP Solenoid shut off valve fails to operate and remains open!

MEL raised (C) !

When asked what does one do in flight, when HYD SYS OVHT occurs? Airbus answer, "10x-9 and that the HYD box will overheat and shear off the HYD drive mechanism, with no further damage", when pressed for more info, nothing cameback.

Therefore, didn't take MEL! 4 hour flight over water at night, problem with this particular HYD system, could only become worse in flight! don't get paid enough money to take that one !
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Old 15th Jun 2009, 00:27
  #43 (permalink)  
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.. which is why the MEL/PUS systems are permissions, not coercive directions. The pilot is expected to consider the facts ON THE DAY and moderate the MEL permission as appears appropriate. ie the pilot can require more restrictions up to and including not accepting the aircraft.

.. all depends on the operator being reasonable and honourable as well, of course.
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Old 2nd Sep 2009, 21:00
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Symptom: Overhead panel black after engaging external power after engine shutdown.

Cause: Fault in WEU

Solution: Momentarily hold "Lamps Test" in "1", this will break through the WEU glitch and allow signals through to the panel lights.

Symptom: Ailerons heavy and stick at full deflection (on ground with no aerodynamic load, this is often dismissed as normal!).

Cause: May be pulleys slipping off their main bearings causing the retaining washer to become conical, in turn causing friction.

Solution: Ask tech to look at aileron pulleys and their retaining washers.

Symptom: "Avionic Smoke" when powering up avionics in very cold and humid environment. (verify that there is no actual smoke or fire situation).

Cause: Humidity or frost build up in avionic smoke detector.

Solution: Start one engine, open pressure dump valve and apply maximum heating until the warning goes out, may take a few minutes.

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Old 25th Sep 2009, 05:21
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Something to remember about these flying computers.
I have read of SWLT inputs that do not work in this forum.
Take time to positively push each switch and ensure light msg appears or clears. I have demonstrated to junior mechanics that by pushing a SWLT quickly no msg appeared then selecting again but slowly and positively the msg will appear.
When doing soft resets on the o'head panel ensure a reasonable time lag (10-15secs) before reseting not a nano sec. This is a (Ctrl/Alt/Delete) function for your computer not a c/b.
Something to remember when the cockpit goes black.....
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Old 2nd Nov 2009, 23:39
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DHC-6 a great way to build flying time!

God I love Twin Otters! Smoke rolling out from the floor boards with Airconditioning on, getting passed by canadian geese in flight & Greyhound busses on the ground... The only fixed wing aircraft in the world to take off in a nose down attitude... those wacky DeHavilland guys!
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Old 21st Jan 2010, 23:11
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PTU cannot be switched off

Well done not to accept the aircraft. This is not a MEL C item. Acc. Mel 29-23-01 "PTU may run continously when selected AUTO provided operation of the PTU in both directions is checked before first flight of the day."
That also means that in OFF the PTU must stop! Hence this item is a NOGO.
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Old 3rd Feb 2010, 15:35
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Honeywell FMC 757

I hope this in the right place.

FMC all loaded properly with PERF INIT and TAKEOFF data loaded.

Message shows MAX ALT FL XXX, if you go to clear it in the scratch pad your initial fuel will show, but no fuel calculations will show up on LEGS or PROG.

In order to get the calculated fuel back you have to change the cruise altitude on the VNAV page to something it will accept, if the cruise altitude up link was more than what the FMC allows.

This was not taught to me in school nor passed to me on the line, the engineers couldn't figure it out either, I know it seems obvious now, but forgive me I'm a slow learner.
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Old 8th Feb 2010, 13:59
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dhc-6 300 pt6a-27 engines

problem: uncommanded prop feathering after t/o.
action: shut-down as per emergency checklist.
cause: T.B.C, suspected fault in beta sys, will update when I know

Cause : Beta-backup system failure, now Modding to remove the system as it apparently causes more problems than it protects from.

Last edited by mrwebs; 16th Feb 2011 at 06:15.
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Old 28th Mar 2010, 05:54
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"Flight director disagree.
I have never seen this before on an airbus!
AP2 engaged.Modes are v/s and loc with gs armed. Aircraft is cleared to 2000ft and further with the glide.
F/o PFd GS* as glideslope captures at approx 2300ft.Ap1 engaged as plan is practice autoland.
Capt Pfd Alt* as approaching fcu altitude as GS* not annunciated.
AP1 now master autopilot so aircraft attempts to acquire fcu alt and not the glideslope.
Glideslope is now showing fly down so both autopilots and fd disengaged and a manual approach and landing flown.
Does anybody have any ideas as to why this happened?"

My guess is one ILS receiver in a failure mode not understood by the FWC. What about the GS and LOC indications?
Just my 5 cents!
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Old 10th May 2010, 14:44
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MMR1 intermittent failure

After tuning ILS 1 & 2, setting up for approach in marginal weather, noticed that ILS 1 tuning was intermittent (indications switched between freq/course to IDENT/course)...and ILS 2 was rock solid IDENT. This situation prevented a dual autopilot autoland and also NO AIII capability...only the ILS 2 was available for an instrument approach. Next day, after talking to Maintenance regarding the writeup...come to find out that a failure of MMR 1 had occurred...according to them, this never happens! There is no comparator between these and you wouldn't know you suffered this problem until on final and no Cat2/Cat3 capability.
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Old 10th May 2010, 14:53
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Heavy airbourne,I posted the original problem and after a lot of digging in the fcom I discovered that if the aircraft FDchanges to ALT* and at the same time it is in a position to capture GS it will not capture the GS!
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Old 21st May 2010, 01:15
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Thanks, tubby linton!

"It's not a bug, it's a feature."
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Old 5th Aug 2010, 10:26
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ATR 72 Cargo - ELEC SMOKE during loading

Sometimes when in the cargo aircraft during loading they drop a heavy box in the forward door area a couple seconds later the ELEC SMOKE warning comes on with the MASTER WARNING.

Check for electrical fire evidence first! You want to make sure it is really a nuisance and not a real thing. You have time btw. as we are on the ground and all doors open.

You may select OVBD VALVE to OVBD position and wait. Normally it goes away. May be reproduced by jumping up and down again in the door area.

Cause: Dust risen by the falling parcel or jumping
Solution: MX entrance for cleaning up with vacuum

P.S. I've never seen it been done (cleaning up I mean)
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Old 5th Aug 2010, 10:34
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AVRO RJ - FMS with no fuel quantity indication

Problem: One fuel tank quantity indicator may be INOP.

According MEL A/C can be dispatched after dipstick. No problem with that, but:
FMS has no more performance page, no speeds, no predictions on fuel etc.
This is a logical consequence but nevertheless a nuisance.

Back to manual fuel checking etc. Not a problem with this contraption as everything to do this is at hand.

Rises the question - how is this handled in e.g. A320 or 737? More problems with the performance page, speeds etc.?
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Old 14th Sep 2010, 02:18
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FMC fuel entry - MD11 with MEL 28-41-xx

If the FQIS is giving an erroneous indication, it is a simple matter, after starting one engine, to go to the FMC INIT page - FUEL, and deselect FQ (fuel quantity).
By doing this, the FOB is calculated only from the original (blocked) FOB - FF (fuel flow) (as determined from the FF sensors at each FCU (fuel control unit).

By using this method, there should be no incorrectly computed GW, thereby giving erroneous performance/speed data to/from the FMC.

However, your questions asks specifically of the B737/A320 FMCs; I would like to think those FMCs have a similar capability.
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Old 26th Oct 2010, 00:28
  #57 (permalink)  
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Airbus GS Capture.

I have also seen it myself. It's a known fault and the subject of the "No Loc or GS Capture in Approach" OEB. It's corrected by a new standard of MMR.
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Old 26th Oct 2010, 00:50
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A320 legacy FMGC retention of previous VAPP in secondary flight plan.

Here's a good one which I have seen several times and which could catch someone out badly one day. If the previous flight has had the VAPP increased for any reason in an A320 with the of style "legacy" FMGCs and the active flight plan has been copied into the secondary, sometimes it can retain the selected VAPP on the next flight in the secondary flight plan. It should be checked, but one day it will be missed.
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Old 9th Dec 2010, 08:29
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Gulfstream G-159

During takeoff/initial climb the left engine lost power. The flt crew attempted to continue the climb-out, but following the application of water-methanol, the pilot lost directional control. Subsequently, the aircraft banked to the left, entered a descent and impacted between the parallel runways. Injuries: 2 Fatal

Never arm the water-methanol system when already at takeoff power.
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Old 3rd Apr 2011, 09:01
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b737 hydraulic fluid transfer from B to A

Good day, maybe someone now this. During flight and especially landing hydraulic fluid transfer from B to A. It became 100 A and 85 B. No leak found.
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