TravonNicholls

Post-incident investigation needed

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I was flying a KLM 747-400M from EHAM to RKSI today and the aircraft lost Engine 4 electrical generator in the early stages of the descent into RKSI for some unknown reason. The descent was continued and no action was taken. 5 minutes later, Oil pressure, Oil quantity and Oil temperature warnings for engines 1, 3 and 4 sounded and the checklist stated these engines should be shutdown. The affected engines were shutdown and an attempt to start the APU was made. This attempt was unsuccessful as the APU oil quantity was also too low. The aircraft therefore had to land at RKSI with only Engine 2 running normally. Maximum Auto brakes was used on landing due to the inability to use reverse thrust and the brakes became very hot and tire failures were experienced. The aircraft was Taxiied onto Taxiway N5 where it stayed until external power could be connected and Engine 2 was shutdown. The failures experienced were UNPLANNED and the reason they occurred is still unknown.

Can anyone tell me what happened? Was there an oil leak or something?

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Did you check your oil levels before flight? The engines and APU don't have a common oil fill point, so there would have to be 4 separate oil leaks ( basically impossible). Perhaps the engineers forgot to put the oil caps back on the individual tanks after topping them up? :tw_blush: The generator also has its own oil supply, but the generator is driven by the engine. The N2  (or N3 if Rolls Royce engine) rotor must have seized (due to lack of engine oil)

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.... and an attempt to start the APU was made. This attempt was unsuccessful ...

Well that was doomed to failure. The 747-400 APU can't be started in flight. It can only be operated in flight unless it was already running on the ground.

Cheers

JHW

 

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Each engine has its own oil reservoire and a simoultanious leak in 3 of them is close to impossible.

I also noticed PMDG likes to fail several "similar" items at once in the service based failures though.
For example I often get failures of the HPSOVs in multiple engines at the same time, in one occasion even a similar scenario as you described, just that I had oil overtemprature on "just" two engines simultaniously when starting a descend after a BKK-FRA flight. On departure the oil quantity indication of all 4 (CF-6) engines was at 20, so it should have been sufficient for this flight of about 11 hours.

I also pretty often see failures of the fire detector loops in the cargo holds, if one of them fails early in the flight you can tell with 99% certainty that the other will also fail during the same flight.

 

What did the failure page in the FMC show after landing?
After landing I always check this page to check whether my judgements of what was going on were correct. I use it as sort of a feedback from the engineer on the ground.

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But those problem are part of a wrong operation so we have to check with the checklist the correct value of every liquid temperature and pressure or are bug of failure activity even if is disabled?

The other day in a Flight from EPWA to ESSA I got a message of SPLIT IRS OPERATION which disable CAT3 landing operation after reading  I discovered that this are situation if you fly over Polar coordinate but I didn't.

Another episode was that the brakes was so hot that it wasn't possible to stop the aircraft.

In a way it's fun because you really learn how to operate this majestic queen.

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Did you check oil levels before you took off? It does have the option in the FMC to use the last oil level that you had, so if you didn't check and you took off, it's possible you may have run low on oil.

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Could too cold fuel be a part of the explaination? I mean, if the fuel becomes too cold, you get a warning. If you do nothing about it (like descend into warmer air), the fuel will start to become like slush.  I dont know all the inner workings of the 747-400, but I know that using fuel to cool engines is not uncommon. If fuel is used to cool engines, but the fuel movement is hindered because of ice particles, then that could explain your engines and oil overheating. I might be on a wild goosechase though ;)

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I dont know all the inner workings of the 747-400, but I know that using fuel to cool engines is not uncommon. 

Fuel is used to cool the oil (and oil is used to heat the fuel). However, if the fuel gets too cold, the oil is diverted past certain areas of the fuel/oil heat exchanger. This, I assume, has the potential to make the fuel even colder.

A fuel temperature message should be generated if the fuel becomes too cold, but it wouldn't hurt to monitor fuel temperatures in flight.;)

Cheers

JHW

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On 2/25/2017 at 7:11 AM, Captain Kevin said:

Did you check oil levels before you took off? It does have the option in the FMC to use the last oil level that you had, so if you didn't check and you took off, it's possible you may have run low on oil.

Sorry for my ignorance, but if oil is low how do you add......never had that feature before and not sure how to do it.....

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On ‎2‎/‎25‎/‎2017 at 4:33 PM, Qavion2 said:

Fuel is used to cool the oil (and oil is used to heat the fuel).

I thought that was hydraulic fluid rather than oil.

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4 hours ago, pcubine said:

I thought that was hydraulic fluid rather than oil.

Most jet engines have a fuel/oil heat exchanger. Its main function is to heat the fuel coming in from the boost pump, (just prior to the inlet of the engine fuel control).

Though it does provide a cooling effect on the oil, the fuel heating function is the most important part - especially on long duration flights at altitude where the fuel temps can get very low.

Some aircraft (specifically Gulfstreams) circulate hot hydraulic fluid from the engine pumps through coils submerged in  the wing fuel tanks. Here, the main purpose is to cool the hydraulic fluid, with the secondary benefit of warming the fuel in the tanks somewhat.

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I thought that was hydraulic fluid rather than oil.

The 744 has both. The heat exchangers for the fuel/oil are on each engine. The heat exchangers for the fuel/hydraulic fluid are in the tanks.

Cheers

JHW

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17 hours ago, RW23 said:

Sorry for my ignorance, but if oil is low how do you add......never had that feature before and not sure how to do it.....

If you go into the maintenance options in the FMC, it should be there.

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Thanks.....lots of things to look.....often we are just anxious just to fly:biggrin:...

 

And this forum with new look is so slow that drives me to the wall.....something has to be done about it

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On 2/25/2017 at 6:49 AM, Qavion2 said:

Did you check your oil levels before flight? The engines and APU don't have a common oil fill point, so there would have to be 4 separate oil leaks ( basically impossible). Perhaps the engineers forgot to put the oil caps back on the individual tanks after topping them up? :tw_blush: The generator also has its own oil supply, but the generator is driven by the engine. The N2  (or N3 if Rolls Royce engine) rotor must have seized (due to lack of engine oil)

Well that was doomed to failure. The 747-400 APU can't be started in flight. It can only be operated in flight unless it was already running on the ground.

Cheers

JHW

 

Yes I checked the oil levels at departure and they were good. I can't remember exactly but a similar thing happened again on Wednesday while I was flying from EHAM to ZBAA. During the descent I got oil temp warnings for engines 3 and 4 and had to shutdown both of them. I managed to land safely though...but at my origin airport for this last flight, my oil levels were 19. It seems everytime I fly over to that region I have engine oil issues haha.

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1 hour ago, Travon999 said:

It seems everytime I fly over to that region I have engine oil issues

So don't fly there. Problem solved.:laugh:

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1 hour ago, Travon999 said:

During the descent I got oil temp warnings for engines 3 and 4 and had to shutdown both of them. I managed to land safely though...but at my origin airport for this last flight, my oil levels were 19.

You are not understanding the problem.  Your high oil temp is due to low fuel in those tanks and probably has nothing to do with oil levels.  Maybe you are not switching to tank to engine mode?

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10 minutes ago, Captain Kevin said:

So don't fly there. Problem solved.:laugh:

😂😂😂😂agreed!

 

 

 

Travon Nicholls

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11 minutes ago, downscc said:

You are not understanding the problem.  Your high oil temp is due to low fuel in those tanks and probably has nothing to do with oil levels.  Maybe you are not switching to tank to engine mode?

I am switching to Tank/Engine mode though. The fuel levels weren't low.

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You are not understanding the problem.  Your high oil temp is due to low fuel in those tanks and probably has nothing to do with oil levels.  Maybe you are not switching to tank to engine mode?

Dan, if the engines are running, I don't see how low fuel quantities would affect oil cooling. Low-ish fuel quantities are only going to affect hydraulic fluid cooling.

Cheers

JHW

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42 minutes ago, Qavion2 said:

Dan, if the engines are running, I don't see how low fuel quantities would affect oil cooling. Low-ish fuel quantities are only going to affect hydraulic fluid cooling.

Cheers

JHW

Exactly. The oil cooler is supplied by the primary engine fuel line - if THAT runs dry, the engine is going to flame out in any case.

I have never worked on the large GE/RR/PW engines used on the 747 - the largest engines I have experience with are the RR BR715 and GE CF34. But on these smaller engines, the fuel/oil cooler has a thermostatic valve to bypass the oil around the cooler when the oil is very cold, (such as when initially starting the engine on a very cold day). I assume the bigger engines use a similar bypass valve.

If the valve got stuck in the bypass position when the oil is warm, I could see how that could cause high oil temps. I don't know if the PMDG engine simulation is sufficiently detailed to have that particular failure mode though...

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