Aircraft without a loss of oil pressure procedure

[18-Wheeler]

The Metro 3 (SA227AC) has no procedure in the AFM for a low oil pressure.
The Metro 23 (SA227DC) does have a procedure in the AFM for a low oil pressure.

No model of Metro that I'm aware of has a procedure for low oil quantity.

grade-3
(helluva thread for what seems a fairly straight-forward question... )

Indeed.
Please upgrade yourself to Grade One!
It was a simple question, no need to get all bent & twisted about useless semantics.

[SNS3Guppy]

As for my thoughts regarding how a loss of oil quantity may be recognized I have covered that comprehensively, but again it was not in agreement with how you see it, so therefore I am wrong.

Yes, you are.

[Old Fella]

Yes, you are.

Guppy, no surprise to read your response. If you are too embarrassed to concede here you may have been wrong too, even just once, why not PM me with a concession and your C130 experience as a pilot, FE, mechanic and inspector at depot level as I requested.

[aerobat77]

The Metro 3 (SA227AC) has no procedure in the AFM for a low oil pressure.
The Metro 23 (SA227DC) does have a procedure in the AFM for a low oil pressure.

i just took the time and looked again at the AFM of the two types i currently operate in our company :

PA42-720 cheyenne III
PA34-200 seneca II

the cheyenne with the PT6A-41 has a procedure like i wrote some time ago for low oil pressure ans splits it :

- when all other parameters normal and engine response normal reduce power as practicable and land soon as possible
-when engine response and/or other parameters abnormal shut down the engine.

the interesting thing : the small seneca with its turbo charged pistons
(TCM TSIO-360) indeed also has no statement for low oil press in its abnormal checklist.

i must say i never noticed this

but when you read further and go to the engine limits section you have a minimum oil pressure for operating. i am pretty sure that the metro3 somewhere in its engine limits section has also a minimum oil pressure for operating.

so here you have it indirectly- when you loose oil pressure and go below the minimum operating limit you must not operate the engine and switch over to single engine procedures.

both mentioned planes have NO procedure for low oil quantity inflight, but both have a minimum allowed quantity for departing when you do your preflight checks .

hope this helps a little.

[aerobat77]

@old fella :maybe a little off topic, but one question to you- some time ago , as we waited on the ramp for passengers , a military c130 taxied to the runway and took off . (with serious sound on taxi )

it sounded for me that they taxied with 100% rpm- there seemed to be no further spool up of the turbines at initiating the take off roll. is it so? do you taxi the c130 with fully spooled up engines?

[Tmbstory]

Hercules on the Taxi

Aerobat77:

Not sure if I can help but with the L382 version of the Hercules, if the aircraft weight permits (usually under 140000 lbs) the taxi may be conducted with all engines in low speed ground idle. May be the C130 you saw and heard was not using low speed ground idle.

Tmb

[Old Fella]

Taxi C130

Aerobat77. As Tmbstory says, later C130's have a low speed ground idle function, predominately to help control taxi speed and save using either reverse or braking to keep the taxi speed low. Esssentially, the T56 engine operates within a very narrow RPM band, indicated in % RPM. 100% is 13820 RPM and via a 13.54 reduction ratio gearbox gives a prop RPM of 1021 at 100%. Ground operating limits are as follows: Low Speed Ground Idle 69-75.5%, Normal Ground Idle 94-102%, Max Reverse 96-106% and Normal Flight Idle 94.5-100.5%. Propeller Blade Angle at throttle positions below Flight Idle is controlled by throttle position. In the Flight Range RPM is contolled to 98-102% by the Propeller. The only limitation regarding throttle movement is to not move from Flight Idle Position to Full Throttle in less than 1 Second. Power output and RPM increase is absorbed by increasing blade angle. The propeller is fully feathering as well as fully reversible. Hope this is helpful and answers your question. Cant help with any first hand on info post "H" models.

[V1... Ooops]

Grade 3, 18 Wheeler, et al...

I am going to speculate here that aircraft certified under CAR 3 regulations (which might possibly include the Metro 3 and the PA34-200) don't have a procedure for low oil pressure because the CAR 3 cert regulations did not require such a procedure be provided, and that aircraft certified under SFAR 23, or FAR 23 at amendment 7 and later, do have such a procedure, simply because the cert regulations require it.

I have not done any research on this, so, this is pure speculation at this point, but I kind of suspect this might be the case. What got me thinking about this is the model names associated with the Merlin - the numbers '3' and '23' seem to be more than coincidental, as SFAR 23 (a rule that applied to a rather small number of 10 to 19 seaters built in the late 1960s and early 1970s) was the legislation that bridged the gap between CAR 3 cert regulations and the present-day FAR 23.

Michael

[Tmbstory]

Your post#107

Old Fella:

Thanks for your post #107, it was very well explained and put. My experience was only on the L382 which was used in PNG on the Moro oil project.

Regards

Tmb

[Old Fella]

C130

Tmbstory, my pleasure and thanks for your comments. Happy flying.

[aerobat77]

old fella, tmbstory : thank you very much gentlemen for this good explanation !

so it seems that they taxied with normal ground idle and not low idle, that would explain it .

one more question regarding the throttle movement: does the T56 have torque/ temperature limiters installed so you can "firewall" the power levers on take off run ?

@ V1....oops : good point, it may be that they simply did not incorporate such a procedure because the regulations under which this planes were certified did not require it. it would make sense that it is just that simple.

[18-Wheeler]

Thanks chaps, it makes a fraction more sense now.
V1 - seems odd to leave something so important out though.

[Old Fella]

Firewalling throttles

aerobat77, When moving the throttles up from Flight Idle it is not good practice to simply firewall them. Two primary reasons, one it is possible to overtemp the engine, despite it having an electronic fuel trimming function which above 64 degrees throttle angle, (known as cross-over) allows the Temperature Datum valve to "Take" fuel or "Put" fuel to control the temperature in relation to throtle position, this known as Temperature Controlling Range. Below Cross-over the TD valve is only able to "Take" fuel, this being Temperature Limiting range. In colder ambient conditions it is also easy to "Over-torque" the engine, the limiting value being 19600 "/lbs of torque. This is in fact an airframe limitation, the engine mounts being the limiting factor. There is a significant "Ram Rise" in torque as the aircraft accelerates, so setting take-off power is done without undue haste, especially when conducting a rolling take-off. Operating the C130H from McMurdo on the Ross Sea we reached the torque limit not too far above cross-over. Being essentially a constant speed engine there is no real need for rapid throttle movement as the engine does not need to "spool up" and response to throttle movement is pretty much instantaneous. A very good feature in an aircraft which is flown in a tactical role into some very ordinary airfields. I am unsure what the torque limit on post "H" models is, however it remained unchanged from the original C130A right through to the C130H.

[SNS3Guppy]

...why not PM me with a concession and your C130 experience as a pilot, FE, mechanic and inspector at depot level as I requested.

Why, are you hiring?

I think not.

I already have a job, thanks.

May be the C130 you saw and heard was not using low speed ground idle.

All our airplanes used the T56-9's, which didn't have low ground idle. It's distinctive sound when powering down from flight idle. Otherwise, the herc makes it's own very distinctive sound on the ground and in flight.

[Old Fella]

Distinctive sound.

Yes Guppy and the Aeroproducts equipped C130A's with T56-11 power plants and no "Low Speed Ground Idle", in RAAF service, had a quite different sound to the Hamilton Standard equipped aircraft.

Pity about you not being willing to share your C130 experience, not that I would ever be in a position to hire you. I was just interested in a comparison on type between yourself and me. It is unusual to learn of someone with experience as a Pilot, FE, mechanic and inspector at depot level on the one type. Personally, after about ten years on various other types of aircraft as a Ground Engineer, I had 2 years on the C130 at Senior NCO level as a Ground Engineer before transferring to FE. I accumulated a total of 4760 flight hours on type, predominately on the C130A, but also time on the C130E and H models. See Guppy, it's not hard to share, especially when it can be verified.

[johns7022]

Resume comparisons aside...I think we can agree that a low oil pressure indication is a place to start...in my case, the light went on...then to the guage(low)...to the temp(green) to the nacelle...spewing all over..

I'n my case, I chose not to shut the engine down,(probably should have) but pulled the power back on the engine to idle, got it down on the ground ASAP...and shut her down on the roll out...called in the troops...fixed an O ring on a PT6 governor return line, did a flush...added some oil....did another flush at my home base...no problems..

My checklist told me to shut down the engine if the pressure was low...I wanted the engine in case I needed it down low...I was a little worried that my blades wouldn't feather too...because on that plane an unfeathered engine, will make the plane go about about 3000 FPM down...WITH a good engine on the other side....

Bottom line...if you see a low pressure indication .....will you make the right choice under the circumstances....in the real world it's certainly more then just shutting her down...there are circumstances to consider.

[Old Fella]

Low oil pressure

Johns7022. One indication, in isolation, will not always tell the complete story. That is why MEL's are in place to allow aircraft with various engine or system defects to continue to operate. So also, various indications in isolation do not always require the same action and unless certification calls for it, there may not be a Checklist to cover such indications. Commonsense and experience will often lead to a different way of handling any situation. You obviously looked at what was being told to you and took the action that you as the PIC deemed appropriate and, I suspect, was prepared to modify that decision if required and take responsibility for the outcome. That is what our employers pay us, or used to in my case, to do. There have been numerous times in my aviation career where, as a crew, decisions were taken which were either not specifically covered or where the action called for, in the circumstances, was not appropriate. Our subsequent actions were always taken in the belief that we had done the correct thing and in the knowledge that our backsides would feel the pain if we erred. Sounds as though you made the right "D".

[Brian Abraham]

I was a little worried that my blades wouldn't feather too...because on that plane an unfeathered engine

Excuse me. And for what possible reason might not the prop feather, given that it relies on oil pressure to keep it out of the feather position. Ever notice the prop position on shutdown?

Feathering of the propeller, a critical function for multiengine aircraft, is accomplished by allowing oil to drain from the propeller servo. Feather springs and counterweight forces on the propeller will force the blades into the feather position in the absence of high pressure oil. To do this, the governor makes use of either a feather lift rod or a feather plunger The feather lift rod is centered in the control shaft on top of the governor. When the control shaft is moved to the minimum RPM position, the lift rod pulls the pilot valve into a simulated overspeed condition which allows oil to drain from the propeller. Some governor models use a feather plunger instead of a lift rod. The feather plunger does not directly contact the pilot valve, rather, it diverts governor pump oil to a feather drain tube. Feather plungers react more quickly than feather lift rods and are thus used on higher pressure operation systems such as those found on PT6-67 series engines. Use of a feather plunger bypasses normal porting and allows for quicker feathering of the prop.

[johns7022]

Brian, I love you man...it's like you read the book, but you have never flown a plane...

When the boss gives you a C425 to fly...you can choose to feather the prop..and if the oil that you see coming from the front of the nacel translates into something in the governor making metal...and the prop doesn't feather..

You now get to fly single engine...Vse holds 3000 FPM....let that sink in Brian...put the Fosters down.....3000 FPM....DOWN.....

Can you dead stick a turboprop from 24000 ft into a runway, doing 3000 FPM, all the while the plane wants to flip over with all the drag from the windmilling prop? Then when you get there, if you don't get it right...you can't climb and hit short, with passengers, in the dirt at 3000 FPM...and how's your flare going to be with a windmilling prop...you'll flip the plane...

So I chose to drop like a rock, flight idle, speed brakes, in a FLYABLE plane doing 10000 FPM, and 250kts...and probably have two working engines to guarantee the landing.....

And it worked...hear that? It worked...that's right...let me repeat for the PC pilots...it worked. Downside of my choice...maybe...the oil would have run out, and a bearing cooked...but with no power on it..I doubt it...

People over gear...when you get to fly a plane all by yourself Brian, you might have to make big boy choices like this too.

Now off with you back to the flight sim.

[18-Wheeler]

People over gear...when you get to fly a plane all by yourself Brian, you might have to make big boy choices like this too.

Indeed, and that's why I have stated many times in this thread that with the oil about to run out in the engine I would pull the S&F handle (talking Garrett here of course) so I would not put myself in the position that you put yourself in.