B744 Engine run up
 

I had to do an engine run up today, to find out which engine was causing an oil smell in the cabin.
I assume Boeing gives guidance on allowable power settings with a given fuel load (or aircraft weight). But I don't have an AMM available.
Anyone have one handy?

We managed by the way. Just for a next time ;)

You havent got a AMM??? ..... Unbelivable....Your maintaining aircraft yet you havent got access to to the relevant maintenance documentation legally required to do so , God help us

I can't recall there being any values for stability in the AMM for this. I vaguely recall we had engine run documentation which provided this. Sorry, I've been out of the industry for a while.
However, the AMM did say that there should be sufficient fuel in the tanks by the end of the run to still cover the hydraulic fluid heat exchangers (900kg in outboard mains, 2450kg in inboard mains)

Rgds
NSEU

Thanks NSEU.

as the saying goes, never assume....!

71-00-00-862-031-D00 for minimum weight, thrust balancing and c of g limits!

Table 204. Minimum Gross Weight for Engine Operation (747–400 With RB211 Engines 1 and 4)

Minimum Gross Weight for Engine Operation (High Power)*[1]

Power Level Test Engine
Minimum Airplane Gross Weight*[2]
Power Level for Opposite Engine*[3]
Maximum C.G. (%M.A.C)*[4]

Minimum Idle
350,000 lb (158,757 kg)
0.0
33

Approach Idle
350,000 lb (158,757 kg)
0.0
33

1.174 EPR
350,000 lb (158,757 kg)
0.0
27

1.174 EPR
530,000 lb (240,404 kg)
0.0
33

1.174 EPR
350,000 lb (158,757 kg)
1.174 EPR
33

1.358 EPR
350,000 lb (158,757 kg)
0.0
10

1.358 EPR
750,000 lb (340,194 kg)
0.0
28.5

1.358 EPR
350,000 lb (158,757 kg)
1.174 EPR
31

1.358 EPR
405,000 lb (183,705 kg)
1.174 EPR
33

1.6 EPR
350,000 lb (158,757 kg)
1.174 EPR
11

1.6 EPR
750,000 lb (340,194 kg)
1.174 EPR
28


:eek:

Well, that was a surprise, Spanners :P

I assume the higher fuel weights are to cover the wider range of CGs? Perhaps if the aircraft is loaded for a flight, has a large aft CG, and has a last minute engine problem?

I agree with Brigantee

Mariner and the AMM
 

For those of you bagging Mariner, he is a pilot, not a LAME and I suspect he was requested to run engines either individually, or individually supply the pneumatic system, to determine which engine his aircraft may have been getting contaminated bleed air from.

Still sounds dodgy...

What if he hadn't "managed"?

Who was downstairs? Where were the tests being carried out? Why wasn't engineering doing the tests?

I was taxi/runup qualified on 747 100,200 and 300 with Rolls,Pratt and GE engines.during initial and recurrent training over the years I was never instructed on EPR or N1 limits with regard to aircraft gross weight - is this something that has been made applicable to 400 series only?

Oh no - definitely not.

https://www.flightglobal.com/news/ar...340-60-319969/

i do not see any relevance to gross weight - the problem seemed to be lack of chocks and incompetence.

That was indeed the case Old Fella 😎

And thanks Spannersatcx, that was helpfull. 👍
Looking back, we stayed well within those parameters, even though we had PW4000 engines.

And we did find the culprit, so the mission was succesfull.

Table 202. Minimum Gross Weight for Engine Operation (747–400 With PW4000 Engines 1 and 4)

Minimum Gross Weight for Engine Operation (High Power)*[1]

Power Level Test Engine
Minimum Airplane Gross Weight*[2]
Power Level for Opposite Engine*[3]
Maximum C.G. (%M.A.C)*[4]

747–400B
EPR

Minimum Idle
350,000 lb (158,757 kg)
0.0
33

Approach Idle
350,000 lb (158,757 kg)
0.0
33

1.088 EPR
350,000 lb (158,757 kg)
0.0
27

1.088 EPR
530,000 lb (240,404 kg)
0.0
33

1.088 EPR
350,000 lb (158,757 kg)
1.088 EPR
33

1.207 EPR
350,000 lb (158,757 kg)
0.0
10

1.207 EPR
750,000 lb (340,194 kg)
0.0
28

1.207 EPR
350,000 lb (158,757 kg)
1.088 EPR
31

1.207 EPR
405,000 lb (183,705 kg)
1.088 EPR
33

1.6 EPR
550,000 lb (249,476 kg)
1.088 EPR
14

1.6 EPR
750,000 lb (340,194 kg)
1.088 EPR
22

Being a quad, there is less concern with a 747 jumping the chocks during a high power run than with the big twins like the 767 and 777. Rather, the primary concern is with the side forces on the nose wheels.

Many years ago, I was in the flight deck on a 767 during high power trim runs when the nose gear moved sideways :eek: - I was mildly amazed at how quickly the engine run guy had the throttles at idle :E.
There had been a hydraulic fluid spill near the nose and the tires slipped on the hydraulic fluid. The ground crew reported the nose had moved about six inches - those of us in the flight deck thought it had been more like six feet :mad:.

Just a suggestion but the oil consumption run would be a way of determining this fault, of course running up to 4 engines at power can be impractical and costly so some idea from oil uplifts should narrow the field, older cold air units with oil sumps can produce this problem and the APU has to be eliminated but usually this smell occurs during take off and early climb out. Even the quad B744 will need an opposite balancing engine when power is applied.

You are correct that asymmetric thrust is a high concern on the 777. In fact, it has something called Thrust Control Malfunction Protection. The EEC provides protection against an uncontrolled high thrust malfunction during ground operation and automatically shuts down the affected engine when the thrust lever is at idle, and the engine is above idle speed and not decelerating normally.

Eng3 was already suspect due to it's higher oil consumption.
And the oil smell actually occured during descent and taxi in on the previous sector, which was a bit puzzling. Oil leakage is a known problem on the P&W 4000 series, and there are a number of SB's about oil leakage caused by carbon seal wear and coking.

The engine was subsequently replaced, so the complaint has been closed. It had been due for replacement at the end of the month anyway.

Yes, I'm very familiar with "TCMA" - although not all 777s have it, only the GE90-110B/115B. TCMA doesn't exist on the earlier GE90 or Pratt/Rolls powered 777s. It is however basic on all the newer models - 787 (both engines) and 747-8 - and both the 737Max and 777X will have TCMA.
It's not really there for ground runs (though it would still be of benefit if an engine ran away uncontrolled) - it's there for takeoff or landing where an uncontrollable high thrust event could result in a high speed runway departure.

We had an outboard engine stall on a 744 high power engine run and the aircraft reportedly moved six feet sideways, althought it could have been the same as in your case. Might be a good idea to buckle up for engine runs.

According to my notes, it's not active below 70kts CAS. (EDIT: Not-applicable... Was confusing it with Thrust Assym Protection)

I'm not intimately familiar with the TCMA logic on the GE90-115B, but I don't think that's the case. I am intimately familiar with the TCMA logic on the 747-8/GEnx-2B (which borrowed heavily from the GE90) and there is no airspeed inhibit - only air/ground (granted, relatively elaborate air/ground logic with the default state being air).


At least back when I was observing engine runs, we had more people on the flight deck than there were seats, sometimes a lot more.
I was responsible for the engine running functional test 20+ years ago when we did the first 777. When we did the very first engine run, I counted an even dozen people crammed into the flight deck :eek:. I was stuffed back into a corner, trying to take notes on how I could improve the test. The ECS system wasn't working right, and it was seriously cold on the flight deck. I was crammed next to one of the ECS outlets, and at one point there was snow coming out the outlet - I quickly exclaimed "no wonder I'm cold, it's snowing in here" :E. The mechanic in the right hand seat messed with the ECS controls and the snow stopped.
The next day I was at my desk updating the engine run functional based on what I'd observed, when I got a call from a guy in ECS.
"Are you the person who said you saw snow during yesterdays engine runs?"
"Yes.."
"That's not possible, what did you actually see"
"Well, I observed white particulate matter coming out of the ECS outlet. It floated down and landed on my note pad, where it turned to water".
"Oh..." <click>
:rolleyes:

Standard procedure for our EGR's is to buckle up at all times, and only those required for the EGR on the flt deck!

Our 744's used to spit small chunks of ice out of the ceiling vents on the Upper Deck on humid days. They were large enough to generate rattling sounds in the ducts.

NSEA - apples and grapefruit...
TAC (Thrust Asymmetry Compensation) and TCMA (Thrust Control Malfunction Accommodation) are completely different systems.
TAC is a flight control based system that moves the rudder to compensate for an uncommanded thrust asymmetry - such as an engine failure.
TCMA is resident in the FADEC and shuts down an engine that is at uncommanded high thrust and is not reacting to throttle movement.

Thanks, tdracer. Original message modified.