Questions Regarding Engine Run-Up???

[AeroTech]

Hi,

I have few questions regarding engine run-up in the context of the thread "Engineer death in south tenerife during engine test":

1-During one engine run -up at high power, does the MM states that the opposite engine should also be run-up? and at what power: high power or idle?

2-Just wondering when using "Flags" as visual indicators on engine bleed valves: is it possible to leave reverse cowls open during engine run-up to see these "Flags"?

If I am not mistaken the engine air bleed valves are located on the engine core (medium and high bypass engines). Even if these valves are located on the case fan, the fan cowls must be closed if high power engine run -up is performed. Is this statement is false or true?

Feedback appreciated. Thank you.

[spannersatcx]

Based on 747 eng ground run knowledge/experience.

1/ If running an outboard engine above 1.3 epr (RB211) then opposite engine must be run up to 1.3 epr to balance. So if testing no1, move thrust levers for 1 and 4 upto 1.3 epr then carry on with no1 to required setting leaving no 4 at 1.3 epr.
Inboard engines no balance required.

2/ The 'flags' test you are referring to was on a JT9, which had 2.5 bleed vavles, these were located on the core behind the reversers and opened/closed at a certain power setting and starting, the JT9 has whats called 'RABS' reverse air bleed system, and opened/closed the same bleed valves, so having the reverser deployed would not help at all.

You can't do the 'flags' test as mentioned above on a RB211-524 as the bleed valves are on the core under cowls however you could check for the opening and closing of them by monitoring the egt, there would be a increase or decrease of 40-60C when the valves opened/closed.

These bleed valves are for engine air control, eng bleed offtakes for services are different, HP/IP, these can be monitored through the CMC on 744, or valve position lights on the classics.

Hope that helps.

[sdh2903]

On my experience of Airbus ground running above reply is correct, opposite engine EPR/N1 should be raised to balance, this power is usually above ground idle.

With regard to running with cowls open, this should not be done as you are compromising fire detection and or fire extinguishing systems, dont get me wrong I know it happens but me personally I would always have them closed.

Back to the engineer death, the only way to completely eradicate this from happening is to have engine cages at every airport. Due to costs and time involved in using these this will never happen. Sad when time and money is put before human life.:confused:

[Perrin]

Have had to leave cowls open for some checks and adjustments, remember adjusting oil pressure on JT9 but never above idle. Thanks spanneratcx I will be up all night thinking about the rabs system on the old JT9's now that was real overtime!!

Keep them going safe boys. Peter:ok:

[AeroTech]

Hi

Thank you for your answers.

On my experience of Airbus ground running above reply is correct, opposite engine EPR/N1 should be raised to balance, this power is usually above ground idle.

If running an outboard engine above 1.3 epr (RB211) then opposite engine must be run up to 1.3 epr to balance. So if testing no1, move thrust levers for 1 and 4 upto 1.3 epr then carry on with no1 to required setting leaving no 4 at 1.3 epr.
Inboard engines no balance required

I just need small clarification regarding twinjet:
During one engine run -up at high power in a TWINJET, does the MM state that the opposite engine should also be run-up?

With regard to the statement about leak checking components at above idle power settings, there is still no need whatsoever to be near the engine. Developer spray can be used for leak checking fuel/oil components and developer/tin foil can be used for pneumatic components.
As for trim adjustments, if the components that need adjusting are inside the danger areas for that power settings, you do not go near them.

What do you think about this statement?
Are these developer spray/tin foil efficient to detect leak check?
What do you usually use if you have certain leak check that requires high power (may be at part power around 70% N1) with fan and reverse cowls closed of course.

Feedback appreciated. Thank you.

[SeldomFixit]

Spanners - I'd bow to your knowledge on a good day but 3.5's were the flagged nasties on the JT Nein

[gas path]

Aw come on SeldomFixit we all new that was just a typo....or a senior moment:p:p

<sigh> JT9d I remember when they was 'cutting edge' :}

[spannersatcx]

senior moment most likely:(

Mind you took a while to get spotted.:ok:

What do you think about this statement?
Are these developer spray/tin foil efficient to detect leak check? Yes and no, yes they can and are used, the hard bit is wrapping all the joints/clamps with the foil. In fact I opened an engine up today for something and various components still had developer stpray on them, and they were still not leaking fortunately. I opened and engine once to check for a leak (tin foil method) and it was like a chaffe dispoenser had been set off bits of foil everywhere, I think cooking foil had been used rather than the correct stuff.:uhoh:

When we have found it hard to determine where an air leak is from we have temperature sensative stickers (for want of a better word) and these can be placed at strategic places around an engine to try and find where the hot area is for repetative high nacelle temps being written up.

[Vortechs Jenerator]

Let me just add that No-one goes near large turboprop engines to do anything when it's running because of the VERY obvious danger - so why do it on a jet?

I never advocate it.

I can ALWAYS find another way of satisfying a function/test/check or adjustment. It may take a few more runs but I tend to guarantee all my workmates go home alive at the end of shift.

[sdh2903]

I just need small clarification regarding twinjet:
During one engine run -up at high power in a TWINJET, does the MM state that the opposite engine should also be run-up?

yes on twin jets (airbus again) you bring non test engine up above idle to balance thrust. I have heard stories of an early A320 doing a high power run on one engine with very little fuel on board and the aircraft turning on the spot.

I also find leak detector spray and tin foil methods ok in 95% of tests again just takes a bit of time to get right.

[pjvr99]

.... Let me just add that No-one goes near large turboprop engines
to do anything when it's running because of the VERY obvious danger ...

Vortechs, that's not strictly true, unless I have a death-wish. I work a
RR/Allison T56/501 test cell, and need to go up onto the engine at least once
during the time it is in the cell to physically check for air/fuel/oil leaks - not
everything is visible from outside the safety zone. Using flags to look for
air leaks is almost useless due to prop-wash, even though the throttle is
moved towards reverse. The same needs to be done on the aircraft from time
to time .....

[Vortechs Jenerator]

well if you do that mate, it's your call.

I have 3 turboprop types on my license and I've never done it and never would. As I said my life's not worth it.

Oil drips/seep sources can be seen at shutdown, fixed and run again

Large air leeks can be heard a mile away over a running engine- or any disturbed clamps checked with some speed tape as mentioned.

Fuel leaks as per oil also with a touch of developer spray but I've always found them very obvious.

But as I said, it's your call, we'll agree to disagree

[AeroTech]

Thank you for your posts.

I am glad that you mentioned turboprop run up, I was wondering about this subject.

Do you usually perform turboprop (even for piston engine) run up at test cell with the prop removed or installed?

Is it possible to approach (but not really close) a turboprop (even aircraft with piston engine, and not in test cell) with open cowls and in THRUST REVERSE to have a closer look to the engine?

I read somewhere that the fan of certain turbofan engine can be strapped or locked to perform engine run up (may be just on idle?).
Is this valid only for the old engines or even for the recent engines?
Is this method still used?

Feedback appreciated.
Thank you.

[mrmagooo]

Locking the fan is done on certain aircraft where a 3 engined ferry is allowed (i.e 146 due to inop engine) to get the aircraft to a maintenance base under strict conditions.

As for locking it on a ground runs, this would just cook the engine as it wouldnt get enough air. This for instance is why you never do a compressor wash or fresh water wash on a LF500 series engine below +4 degrees (I think) as the water could freeze the fan.

[stankou]

15years ago, I was working in an overhaul shop in France, on PT6 and PW100 engines. there were two engine test cells. the old one for small PT6 serie and 1800CA3 was using a short propeller. But due to the propeller blast, it was not very easy to go the noisy room to detect dynamic leaks.
The new one was using a hydromechanical shaftbrake for the large PT6 series and PW100 series. Everything was static and quiete in the room (exept the noise), really more comfortable to have a look.

[AeroTech]

Hi guys,

Thank you for posts

Here a quote from another aviation forum that I mentioned in my previous post:
As to strapping the fan, I looked this up in the A310 mm, though Im pretty sure it applies to all JT9's, sorry cant link it.
The mm says you CAN use this procedure while performing test 03. Test 03 is basically a leak test which is required after the replacement of many engine components. P&W calls it a "locked fan rotor ground run". The mm is very specific about how you strap the fan, they call for installing seven straps which must be woven through the fan blades at specific clock locations. The straps must be positioned "outboard of and against the mid span shroud as far outboard on fan exit vanes as possible".
The advantage of using this procedure is you can run the engine with ALL of the cowling open. The disadvantage is it obviously takes lots of time to set up and you are supposed to have fire fighting equipment standing by because the engine fire bottles will be ineffective with the cowling open. You can not go above ground idle. As an alternative you can do test 03 with the cowling closed (no straps) then open it up and look for leaks.

I am wondering if this method is still applied for the recent engines?

Feedback appreciated.
Thank you.