Aircraft without a loss of oil pressure procedure

[SNS3Guppy]

We had no fuel computer. The engine has a fuel controller, which is hydromechanical, but no computer. EGT overshoot was entirely a function of the user.

I realize you're doubting; your posts are dripping with doubt. I've not only used airframes with TPE-331's, but am a check airman in one of them. I flew not only M18T's with Garrets, but also with PT6's, as well as AT-802's, also with PT6's. However, I have flown several aircraft types with TPE-331's, using -10's and -11's.

but here we may have the difference that on a C441 the engines were rated at just 636HP each side and especially the 331-10 laughed about putting 636 horses to the gearbox.

We were restricted to 985 hp, I believe, given the original engine installation. Emergency output was in the order of 1100 hp.

on the single shaft direct drive tpe331 the rpm change is exactly ZERO when you push the power lever forward . on the split shaft pt6 the prop rpm would stay the same but the Ng would indeed change.

Propeller RPM should not vary, particularly in the type of flying you've probably done. Our airplanes were set up to produce high drag at idle (Honeywell allows a wide range of settings and rigging with the TPE-331, while remaining within tolerance; ag/fire airplanes are rigged differently than what you've probably flown). Idle power caused such an abrupt drag rise that one was thrown forward in one's shoulder straps in level flight. It was a very useful tool for steep downhill runs, particularly behind leadplanes or other tanker aircraft. It did produce RPM variations, as does the use of the speed lever (dropping from 100% nominal to 96% in that rigging installation).

As for your assertion that "on the split shaft pt6 the prop RPM would stay the same but he Ng would indeed change," have you any PT6 experience? Propeller RPM doesn't stay the same at all, and can vary considerably.

You're getting rather far afield when the topic is engine oil; a point you appear to have missed entirely.

You appear very concerned about my experience behind the -10 motor on a hillside years ago. You needn't be. You seem concerned that the loss of torque was caused by the loss of engine oil. You needn't be. It was, as confirmed by a team of investigators, with whom I worked, while making that determination, on site. Also confirmed by Honeywell. The point isn't to entertain the finer elements of fighting fire or Garrett operation, but to address a low oil quantity situation or loss of oil in flight. Again, in that particular case, the manufacturer stated that the engine would run for a half hour with no oil, and in that case, while there was no oil to actuate the propeller (and thus develop torque), the expected oil temperature increase or other manifestations of low oil didn't happen. That's the point. Perhaps you can start another thread regarding the TPE-331, as it concerns you so.

[aerobat77]

"We had no fuel computer. The engine has a fuel controller, which is hydromechanical, but no computer. EGT overshoot was entirely a function of the user."

you can look here

http://www.airweb.faa.gov/Regulatory_and_Guidance_Library/rgMakeModel.nsf/0/2c8af3bbc45fc47186256d96005eb743/$FILE/E4we.pdf

, especially notes 17 and 20 of the TCDS for the 331. the series 8 thru 10 are normally equipped with EGT limiters and and EEC. the EEC may also incorporate a computed EGT with variable redline due to ambient conditions.
but not knowing the dromader installation it maybe that here it was just a hydromechanical fuel control unit.

"Propeller RPM should not vary, particularly in the type of flying you've probably done"


well, on a single shaft propeller rpm is a direct function of turbine rpm, thats why you of course have only one rpm gauge at a tpe331 - when the prop is turning 100%, the whole engine is also turning 100%. touching the power lever has no effect in engine speed , just prop blade angle.

inflight you have 100% take off climb and land and 96% for cruise. thats all. you set it with the condition or speed lever, not with the power lever like you know.

"have you any PT6 experience? Propeller RPM doesn't stay the same at all, and can vary considerably."

yes, i am riding now a cheyenne III ( PT6A-41) leftseat, the 441 experience from the past was rightseat. ( TPE331-10 conversion, the original powerplant of the conquest is a TPE331-8)

propeller rpm stays at the pt6 the same when you touch just the power lever ( inflight) !!! you can change the prop rpm with the prop lever, and due to the fact that here you change just the prop rpm and not the speed of the core you can change it in a wide range. so you also have here a prop and core rpm gauge since on the pt6 prop rpm is not a direct function of the core speed like it is on a tpe331.


you,re are right that this is not fully the theme here- the basic question is about procedures for loss of oil pressure. it is interesting anyway, i - kepping fingers crossed- never had such a problem, neiter on the tpe331 nor on the pt6a now.

[18-Wheeler]

Quick question - I assumed that when the oil finally ran low enough and you did nothing the first thing that would get your attention would be the prop going into coarse pitch or maybe even feather? Aerodynamic forces and so on?
Anyway, I figured if it did that it'd be a very bad thing as the engine would still be making a heck of a lot of torque then suddenly be fighting against a very high load - the fuel bypass valve would try to compensate but from what I remember they can only bypass 90 lbs flow and so there's still a good chance the engine would cook itself in less than a second.

That sound right?

[Brian Abraham]

the manufacturer stated that the engine would run for a half hour with no oil

Flying a single engine Huey (Lycoming T-53) had just landed when the master caution came on, check annunciator panel and "engine oil pressure" is lit, check gauge "zero PSI". Instant decision to take off and get ourselves as far away as possible. Airbourne for a few minutes when the wingman says"you got 30 feet of flame out the tail pipe". No sooner were those words received and the engine chip came on, where upon we put it down. But the all important degree of separation from the previous landing site had been made. Hole in oil cooler had dumped all the oil.

Flying a twin helo off shore had me scratching my head. Had just taken off from a rig a settled in the cruise for the next rig when the oil pressure on one engine dropped to the top of the yellow range and was fluctuating quite a bit, where normally the needle just didn't move. Additionally the oil temp had dropped 10°. No checklist for this and I'm scratching my head as to possible cause. Anyway, engine to idle, pressure remains in the bottom of the allowable range, so head for home with the engine at idle. Climb out after shut down to find a large puddle of oil on the tarmac, check engine, no oil. Split in the line from tank to engine, so along as the engine was running it sucked air in through the split, aerating the oil and causing the loss of pressure, and at the same time cooling the oil. As soon as the engine was shut down it just dumped all the oil out through the split line. Could have been interesting if a problem had developed in the "good" engine which required shutdown, and we had already shut down the one with oil pressure issues and tried to restart it. One old sage said "never shut down an engine capable of producing power".

[Kengineer-130]

I maintain and build turboprop engines for a living, I think the original post has somewhat been lost in the smoke here.

On a turbofan engine (or piston for that matter), the oil pressure would be directly responsible for the life of the engine, as it lubricates the rotating components. As such, immediate shut down would be advised if it were possible following loss of positive oil pressure, without any other clarification of the engines condition.

On a turbo prop, a loss of prop oil pressure should not result in zero torque, it should only allow the prop to travel to the low pitch stop, or fully fine. In this instance, it should still be possible to develop useful thrust for a limited period of time, such as in guppys case. Shut-down would be reccomended as soon as possible, due to the possibility of the prop assembly siezing & possibly detatching due to failure, but even with a severe leak a small amount of running "dry" would be preferable to total lack of thrust in a critical situation. Obviously it depends on the system in use, but if the engine and prop have a common oil system, then the limiting factor would be the engine (In my humble opinion), as it will take less abuse than a prop!

Generally, larger aircraft/ engines have more indications. The C-130's I work on have oil pressure for the RGB and power section, oil temperature, and oil quantity. In such circumstances, loss of say the oil quantity indication isn't a major problem, as if you have good T's & P's then the engine will be safe.

However, if the oil pressure falls or indication is lost, or the temperature is uncontrollable, the advice on the FRC's is to shut down immediatly unless the situation is critical. Helps having another 3 engines to rely on though

[grounded27]

One old sage said "never shut down an engine capable of producing power".

Why not unless you have 2 or 3 more, not an ETOPS fan.

[dixi188]

I used to be on the L188 Electra and had several in flight shutdowns.
There was no check list for loss of oil contents, but common sense should help.

On one occasion we were slowly losing oil contents from one engine so elected to shut it down in the cruise and re-start for approach.

On another occasion the Captain did not want to shut down until we had Reduction gearbox "Lo Oil Press" indication. This ended up with a shutdown as we turned finals. Not the best time to be doing this. Much better to shut down early and get set up for an engine out landing.

[aerobat77]

i just looked at the abnormal checklist of our cheyenne III.

it is splitted there :

when the low oil pressure warning comes on and all other parameters ( ITT, Oil Temp etc) are normal it calls for reducing power as soon as practicable and land as soon as possible and be prepared for a sudden engine failure

when oil temps and ITT is simultany rising it calls for shut down the engine immedietaly and continue with single engine procedures.

on a twin or more engine i think i would shut it down even when it seems to respond when i do not need it at the moment and i can stabilize the plane single engine.

keep on running may result in a catastrophic engine burst / prop shaft failure, engine fire etc etc some time later and then you have a more worse problem.

in a single engine plane i surely would let it run until it carries at least its own weight when there is not a possibility for an immediate landing.

[SNS3Guppy]

but not knowing the dromader installation it maybe that here it was just a hydromechanical fuel control unit.

The 331 installation in that airplane was a mid-time engine out of a Jetstream, and was hydromechanical only. It was installed and rigged specific to the operation for which the installation was conducted.

inflight you have 100% take off climb and land and 96% for cruise. thats all. you set it with the condition or speed lever, not with the power lever like you know.

That is not the case given the rigging of that engine, which was specifically intended to produce extremely large amounts of drag at idle to use as a speed brake during steep, downhill runs. Additionally, speed on that engine is a function of both propeller and fuel control working in concert. The TPE-331, and the T-56 are two of the most complex aircraft engines built, particular to their rigging and mechanical operation. So long as both the fuel control and propeller governor are supplied and able to perform their functions in good working order, you'll see no RPM fluctuation in the type of operations with which you're probably familiar.

Lose the oil out of the engine, and you have an entirely different motor up there.

I have been behind a TPE-331 when a failed rigging assembly and other problems combined to cause severe surging, with rapid, significant RPM and torque fluctuations; significant enough to throw me forward in my seat, and throw me back against the headrest repeatedly. The end result was a tug of war between the overspeed and underspeed governors, a problem with the speed lever, and an internal problem with the motor itself. In that event, I jettisoned the load and prepared to put the airplane in the treetops. I can assure you that the RPM varied far more than between 96 and 100%.

well, on a single shaft propeller rpm is a direct function of turbine rpm, thats why you of course have only one rpm gauge at a tpe331 - when the prop is turning 100%, the whole engine is also turning 100%. touching the power lever has no effect in engine speed , just prop blade angle.

The TPE-331 is not a "single shaft" motor. It is a geared, driven propeller, as opposed to the PT-6 which uses a free turbine, but it is decidedly NOT a "single shaft" motor. You may be thinking in terms of a piston direct-drive engine, which is not the case with the TPE-331. When you say the propeller turning at 100 percent is the same as the engine turning at 100%, hopefully you understand that while the engine is turning at nearly 42,000 RPM, the propeller is only turning at 1,500 RPM.

The engine low RPM in flight, and the top RPM on the ground in beta, is controlled by the underspeed governor, which is a fuel governor. The propeller upper speed is controlled in flight by the propeller governor, which is used to prevent the engine from overspeeding and to regulate RPM in governed operations. The rigging of both these governors, as well as the engine rigging, is given wide lattitude and still considered correct by the manufacturer. What you see in your Conquest is not necessarily what you can see and expect in a different installation. Further, much like the PT-6, various iterations of the engine can have vastly different restrictions, power settings, torque limits, temperatures, etc.

In addition to the propeller governor, also provided is a fuel topping overspeed governor, restricting fuel flow to the engine as well as the propeller governor using engine oil to control the propeller (and thus slow the engine). In the event of a torque loss, the propeller governor will initially attempt to increase propeller blade angle as an "NTS" (negative torque sensing) function in order to load the propeller and thus the engine, and restore positive torque to the engine. If this fails and the engine attempts to overspeed, the overspeed governor will take fuel from the engine. If oil is lost and the engine cannot produce torque through the engine, the engine may attempt to overspeed, and the propeller governor, no longer able to initiate NTS action, may lead the overspeed governor to pull fuel, instead.

Throughout the full range of operation, the various components of the engine “talk” to each other through feedback rods, valves, and preset limits in the engine, fuel controller, and propeller governor, as well as the underspeed and overspeed governors. The exact relationship of these components is variable according to the way in which a particular operator desires the engine to be set up. For example, one operator may establish the rigging such that at idle the engine is operating with substantial drag, whereas another may have the engine operating with residual thrust at idle; both can be within the manufacturers parameters.

The speed lever to which you refer does functions beyond those found on two-lever PT6A installations. While somewhat similar as setting high and low idle, the speed lever sets the underspeed governor, and also as propeller RPM control. The setting of the underspeed governor may not be established at the 96% with which you're familiar, and thus the Garrett can operate at a substantially lower speed, depending on the way in which the engine is rigged. It's also important to note that some garret installations use three levers, some two, and the functions of the lever are different, depending on the installation. It's also important to note that contrary to your own experience on the 331, torque limiters do not necessarily prevent temperature excursions; on many PT6's, temperature control is entirely within the purview of the pilot, and nothing exists to prevent the pilot from overtemping the engine.

yes, i am riding now a cheyenne III ( PT6A-41) leftseat, the 441 experience from the past was rightseat. ( TPE331-10 conversion, the original powerplant of the conquest is a TPE331-8)

propeller rpm stays at the pt6 the same when you touch just the power lever ( inflight) !!! you can change the prop rpm with the prop lever, and due to the fact that here you change just the prop rpm and not the speed of the core you can change it in a wide range. so you also have here a prop and core rpm gauge since on the pt6 prop rpm is not a direct function of the core speed like it is on a tpe331.

What you're referring to is a constant speed propeller. The propeller RPM on the PT6A does not remain constant, however, and varies according to the propeller RPM setting, as well as the power setting. It does not necesarily remain constant; only constant within a governed range. Once the propeller reaches it's pitch limits, it no longer maintains a preset range. RPM does, in fact, change on both the garrett and on the Pratt.

Quick question - I assumed that when the oil finally ran low enough and you did nothing the first thing that would get your attention would be the prop going into coarse pitch or maybe even feather? Aerodynamic forces and so on?

The engine did not feather with oil loss. I was unable to get any usable torque out of it, as there was no oil to regulate the propeller mechanism. There was no feathering action. It continued to rotate, producing no usable thrust.

During the steep descent, I was supposed to stay tucked behind another airplane, an Air Tractor AT-802. Given the braking effect of the propeller installation on the airplane I was flying, I should have had no difficult on the steep descent maintaining a position behind the 802. I was unable. I kept gaining on the 802, and had to pitch up and do tight, narrow S turns to keep my slot. Initially I noted the usual NTS action in the descent, but was far too occupied in the canyon with trying to see (the windscreen was covered in ash, and I was flying into an evening sun, and operating between two rocky faces while trying to keep a loose formation slot) outside, to pay a lot of attention. The inability to slow or keep from overaccelerating on the lead airplane was an important clue, but the problem didn't manifest itself until I reached the box canyon at the bottom. My target there was some structures, and I was tasked with doubling the retardant from the airplane ahead of my on those structures, before making a hard right turn and exiting a narrow burning canyon.

I found that my speed was high at the drop point, and given the narrow window for that airplane (about 15 knots; too slow and one stalls, too fast and one pitches excessively or uncontrollably on the drop), I elected to go around. I pushed the power up, and at first noted only the expected increase in EGT and feel through the airframe (vibration as power increased), with nothing amiss. It was when I began to lose energy and glanced at the torque that I knew I had a problem, though I had a mental disconnect as to what it could be. I thought perhaps I had a sheared shaft, though the lack of overspeed dictated otherwise. That I had normal engine response, but no torque, was puzzling. It wasn't until later when we attempted to drain oil for samples that the answer became clear; no oil, no torque, no torque, no thrust, no thrust, no fly.

Anyway, I figured if it did that it'd be a very bad thing as the engine would still be making a heck of a lot of torque then suddenly be fighting against a very high load - the fuel bypass valve would try to compensate but from what I remember they can only bypass 90 lbs flow and so there's still a good chance the engine would cook itself in less than a second.

If the engine were producing torque, that wouldn't be a bad thing at all. It would be a good thing. The problem is, it ran like a top, but produced no torque, because there was no oil for the propeller governor to port, to increase pitch to obtain torque.

The engine won't cook itself in a second. Again, Garrett (Honeywell) stated that the engine has been shown to run for 30 minutes with no oil. I was quite amazed at how well it functioned without oil, and at Honeywell's admission on the fact; it's a testament to one tough, well built engine (except for those pesky bearing seals).

The C-130's I work on have oil pressure for the RGB and power section, oil temperature, and oil quantity. In such circumstances, loss of say the oil quantity indication isn't a major problem, as if you have good T's & P's then the engine will be safe.

The C-130 (and L188, for that matter, even though the Electra/P-3 does use upside down engines) is a bit of a different animal, as it uses a separate, pressurized sump of H-5606 for the propeller; it doesn't use engine oil to control the propeller, or lubricate the gearbox. It's hydraulic fluid, instead. Without running over that ground again, one can visit http://www.pprune.org/archive/index.php/t-380365.html for specifics.

when oil temps and ITT is simultany rising it calls for shut down the engine immedietaly and continue with single engine procedures.

Again, this is what we really come back to with this thread; the loss of oil in the engine. Conventional wisdom says that a loss of oil will produce high oil temperatures (and perhaps low pressure indications). This may not be the case, at all.

Setting aside the Dromader incident, which has now been thoroughly beaten to death, I had an engine failure last year in a piston twin that was being flown following installation of two new engines. The flight was a test hop for the maintenance department, and during the flight, I saw the oil pressure and temperature almost simultaneously drop to nearly zero. My first inclination leaned toward an electrical failure, but that wasn't the case. The propeller was able to be feathered, and an uneventful return to land was made. On exit, I found that the nacelle and the side and back of the airplane was covered in oil. Upon removing the cowl, I found a shiny new plug, sans safety wire, laying under the engine. We had very rapidly lost the oil, and without oil, there was no pressure, and without hot oil flowing over the temperature sensor, there was nothing to sense.

One might have been forgiven for misinterpreting the lack of temperature, but only if one had been taught to expect high temperatures with oil loss, Low pressures may not be evident, either, depending on where the loss has occurred or is occurring, particularly if the oil loss isn't occurring in the pressure side of the system. One may not notice it at all until all the oil is gone, or until the scavenge/pickups/oil pump begin to cavitate. Depending on the motor, waiting that long may be too late.

As far as your cheyenne, rising oil temperatures and rising ITT is very different than low oil quantity; the chief concern there is generally the ITT, which poses a much greater immediate threat to engine components than the oil temperature or supply. What is making the ITT rise is of concern, and if it can't be maintained within limits, of course you'll want to shut it down. You're talking about the difference between an engine that's making power, and one that isn't operating properly. Not the same thing.

You're confusing your peas, and beans.

on a twin or more engine i think i would shut it down even when it seems to respond when i do not need it at the moment and i can stabilize the plane single engine.

keep on running may result in a catastrophic engine burst / prop shaft failure, engine fire etc etc some time later and then you have a more worse problem.

There's a lot of wisdom in the old counsel not to shut down a motor that's still giving something back to you. I realize that your Cheyenne may seem like the bees knees and a whole kit and caboodle of power, but it's a light twin, none the less, and you shouldn't get too enamored with the power that you've got left.

I had a discussion some years ago with the chief pilot of a charter ambulance operation regarding his King Air 90's capability on one engine. We agreed on an aerial demonstration when he insisted that the airplane would go around on one engine. The flight took place at Reno, Nevada, which at that time of year was both hot, and high. He insisted he would go around on one engine with a nurse, patient, and medical kit aboard, at gross, in the summer. He found out he was wrong, and by the time he got to that point, he was in tears, begging for the engine back, and looking up at telephone poles. He was absolutely silent on the flight home, and I didn't talk to him again, until he was fired a year later. He works for the FAA now, and is still probably handing out bad advice.

Point is, don't get too confident in what your airplane will do on the remaining engine. You might just lose that one too. Then what will you do?

Why not unless you have 2 or 3 more, not an ETOPS fan.

Of course not, and for good reason. You're flying a Cheyenne. ETOPS really isn't in the cards.

[Old Fella]

C130 Reduction Gearbox

SNS3Guppy. I note in your post of 30Nov2010 at 1232 hrs you state, if I read it correctly, that neither the C130 Hercules or the P3 Orion/L188 Electra use engine oil to lubricate the reduction gearbox. I won't enter into the "upside down engine" bit, other than to say the reduction gearbox on the C130 is mounted so as to have the prop shaft above the engine air inlet duct and the P3/L188 has it mounted so that the prop shaft is below the air inlet duct. The reduction gear box on both, however, is most certainly lubricated using engine oil (MIL-L-7808) which is supplied from the same oil tank as the engine. I have not operated the P3/L188, but flew well over 4000 hrs as a C130 F/E (A-E-H models). The Oil quantity, Oil temperature, Engine Oil Pressure, Reduction Gearbox Oil Pressure and Oil Cooler Flap position were all provided with indicators as well as a "Eng Oil Low Quantity" annunciator which could be triggered by any of the four engines. As can be seen, loss of oil quantity would readily be evident in a number of ways. Usually low oil quantity would be accompanied by higher oil temperature and lower oil pressure with the liklihood of the oil cooler flap for the low oil quantity engine being further open in an endeavour to maintain the oil temperature within the normal operating range.

[aerobat77]

"The TPE-331 is not a "single shaft" motor. It is a geared, driven propeller, as opposed to the PT-6 which uses a free turbine, but it is decidedly NOT a "single shaft" motor. You may be thinking in terms of a piston direct-drive engine, which is not the case with the TPE-331. When you say the propeller turning at 100 percent is the same as the engine turning at 100%, hopefully you understand that while the engine is turning at nearly 42,000 RPM, the propeller is only turning at 1,500 RPM."

dude, respectfully , what the hell are you talking??? the tpe331 IS a single shaft propeller turbine, of course geared like every turboprop is since the rpms of the turbine shaft are not applicable for a propeller. the pt6 free power turbine is geared as well to the propeller, thats not the clue. and no - i am not thinking in terms of a piston where propeller speed is engine speed 1:1. ( there are also some geared engines)

the engine turns at 100% 41730rpm where the prop 2000rpm or with another gearing, 1591rpm.

because ( OF COURSE!!!) prop rpm is not turbine rpm in any turbine you have regarding speed the gauge in percent and not rpm. but again- 100% turbine speed at the tpe is always 100% prop speed as well, thats why you had in your dromedar just ONE speed gauge and not two like in a pt6. at the pt6a 100% prop speed is not always 100% core speed ( gas generator)


the main difference between a singleshaft and a split shaft ( free turbine) is that at the singleshaft all compressor and turbine stages are on one shaft and via the gearbox directly connected to the prop. so- when you at the tpe331 slow down the prop you slow the whole engine including the compressors. the compressors have only a narrow band for delivering high output and so you can only at the tpe331 operate inflight between 96-100 %

the t56 goes one step further and runs inflight always 100% speed.

at lets say the pt6 the power turbine is NOT mechanically connected to the compressor stages and when you here slow down the prop you will not slow the compressors. thats why you have have a wider range of changing prop rpm.

you dont believe?

Garrett TPE331 - Wikipedia, the free encyclopedia

read that this thing IS A SINGLE SHAFT turbine...

the T56 is also a singleshaft, of course a much bigger one.

and maybe some other can confirm here.

the other comments of you ( NTS e.g) seem correct to me.

regarding constant prop speed at a pt6... just believe me it will stay constant ( inflight) until you touch the prop lever and set a new target prop speed. only power changes do not change prop speed, just core speed.

when you,re talking about drag in the descend- the most drag you have when the prop turns full rpms - ( and at your tpe in this case the whole engine does like said)


"As far as your cheyenne, rising oil temperatures and rising ITT is very different than low oil quantity; the chief concern there is generally the ITT, which poses a much greater immediate threat to engine components than the oil temperature or supply. "

the ITT at the pt6 without oil MAY rise through an indirect phenomena... when the core starts to size due to a lack of lubrication the fuel control unit will try to keep its speed introducing more fuel ( and so the ITT rises) . a sudden ITT rise witout power changes should be an eye opener at any turbine.

"There's a lot of wisdom in the old counsel not to shut down a motor that's still giving something back to you. I realize that your Cheyenne may seem like the bees knees and a whole kit and caboodle of power, but it's a light twin, none the less, and you shouldn't get too enamored with the power that you've got left."

you are absolutely right here, one main thing some people sometimes forget at all is that the single engine performance is based on a clean configuration. when you short before touchdown have gearand flaps dropped , and then decide for a single engine GA and forgot to retract all this you may run out of power.

in clean configuration the cheyenne III nevertheless has enough juice to perform a go around on one engine, that is not that big deal.

its a general question: run an engine without oil until it dies or shut it? on the one hand you may shut an thrust producing engine and then need the thrust later , on the other hand let it run may result is a severe explosive engine damage with all the problems to you... well, there is no checklist for.

the part from the PA42 abnormal checklist i posted here give just basic rules : let it run carefully when all other parameters and engine response is normal, (and with much luck you just have indication fault)

and shut it when other parameters are also abnormal and you may deal with an engine burst or fire when you run it until it dies.

[18-Wheeler]

All very interesting ....

But back to the question - If the engine is about to run out of oil, as I understand it now it looks like the prop would go into full-fine pitch. That's bad if you shut the engine down due to the high drag, so you'd be best to pull the Stop & Feather while you still have some control over the prop.
That sound reasonable?

I previously thought that the forces on the prop would cause it to coarsen-up as far as it could and I would have pulled the S&F without hesitation, but it's still a valid action no matter which way the prop blades go.

[aerobat77]

good question... i,m not sure if the prop in this case will go in fully fine... when it does so and just stays there since the governor cannot control blade angle anymore you may go with the turbine still developing power in a massive prop overspeed ( or on a singleshaft a whole engine overspeed) which is also not pretty. fully fine on other hand means that you should be able to produce thrust when the engine still sends power to the gearbox

due to shut and feahther... well, it may depend on engine type. the pt6 does not have any locks and should feather anyway when you shut ( like it feathers on a normal shutdown even when you leave the proplever fully forward)

the tpe as well other singleshafts do not feather on a normal shutdown (since you here spin on startup not just the core but the entire engine and a feathered prop would cause many many drag on startup) - here maybe you have to react quick and feather until you loose any control of the prop , maybe. i cannot tell you from experience, never had this.

[SNS3Guppy]

the tpe as well other singleshafts do not feather on a normal shutdown (since you here spin on startup not just the core but the entire engine and a feathered prop would cause many many drag on startup) - here maybe you have to react quick and feather until you loose any control of the prop , maybe. i cannot tell you from experience, never had this.

Of course the TPE-331 propellers will feather on shutdown. That's why you hold it in reverse during the shutdown, to put it on the start locks. If you don't, it will feather, and you'll have to get it back out of feather and behind the locks for start. You previously indicated that you've operated the TPE-331. Do you remember taking the prop off the locks after engine start by moving into the reverse range before restoring normal thrust for taxi?

But back to the question - If the engine is about to run out of oil, as I understand it now it looks like the prop would go into full-fine pitch. That's bad if you shut the engine down due to the high drag, so you'd be best to pull the Stop & Feather while you still have some control over the prop.
That sound reasonable?

That really depends on the engine. Generally, when out of oil, propellers on turbine engines will feather. On most piston airplanes, the default spring loaded position is to low pitch, on the stops. This is not always the case. Some propeller systems will move differently, and some can't be feathered without oil; as oil is used to drive the propeller to feather using an electrical feather pump (hamilton standard hydromatic, for example).

[18-Wheeler]

That really depends on the engine. Generally, when out of oil, propellers on turbine engines will feather. On most piston airplanes, the default spring loaded position is to low pitch, on the stops. This is not always the case. Some propeller systems will move differently, and some can't be feathered without oil; as oil is used to drive the propeller to feather using an electrical feather pump (hamilton standard hydromatic, for example).

Thanks - It just confirms what I said about shutting the engine down with the S&F while you still have control, as either situation is rather bad.
I'm still surprised that there was no procedure for this, it could catch you out quite badly if you weren't experienced enough to realise what was going to happen and there was no checklist to guide you.

[Old Fella]

Propellers

18-Wheeler. As Guppy has said, it really depends on which type of aircraft you are operating as to whether or not the propeller will be controllable in the event of loss of engine oil quantity. The Hamilton Standard props with which I am familiar, and most others with which I have had experience relied on either engine oil, or a self contained hydraulic system, to allow control of blade angle in normal operation or feathering in the event of engine shutdown airborne. The engine oil reservoir on those which relied on engine oil to feather the prop usually had a standpipe below which no oil would be available to the engine lubrication pump but which would ensure sufficient oil was available to the electric feathering pump to complete the feathering of the prop. If oil pressure to the prop was lost for some reason such as a blown seal within the pitch changing mechanism the propeller would, due to Centrifugal Twisting Moment, move toward fine pitch as far as the "low pitch stop" would allow. This allows the prop to act as a fixed pitch prop. If oil pressure to the engine is lost due to loss of oil quantity or any other reason then, of course, the engine would need to be shut down.

[aerobat77]

"Of course the TPE-331 propellers will feather on shutdown. That's why you hold it in reverse during the shutdown, to put it on the start locks. If you don't, it will feather, and you'll have to get it back out of feather and behind the locks for start. You previously indicated that you've operated the TPE-331. Do you remember taking the prop off the locks after engine start by moving into the reverse range before restoring normal thrust for taxi?"

yes, you are right, giving a briefly reverse burst after startup was a common procedure for surely removing the start locks. but we did not shut ( in everyday business) holding in reverse , just in beta taxi range, that worked. that is valid for the 4 bladed hartzell props we had installed.

generally, at least on a 441 you had two ways in shutting : a normal shut with the stop button an an emergency shut with the condition/speed lever pulling all way back in the emer-shut/feather position. in this case the prop will/should feather.

what i think we both agree is that the tpe331 has to be shut without feathering the props on a normal day.

its a very interesting question : will the prop feather by alone without oil when the turbine still runs? i do not know, the checklist does not cover this. but when it does you will surely loose any engine thrust from the prop.
on a singleshaft like the tpe by this the whole engine will be stopped.

i think you incident on the dromader does not cover this- the prop did NOT feathered after loosing oil, it kept on running when i understand you right.

what we can say: it is technically IMPOSSIBLE to keep a tpe331 running with the prop feathered- instead of a pt6 where stopping the prop will not stop the core

[411A]

But back to the question - If the engine is about to run out of oil, as I understand it now it looks like the prop would go into full-fine pitch.

It depends on the specific engine type.
The PT6-20/27/28 types...loss of engine oil quantity, the propeller will feather.
I know, because, I've had it happen twice on BE99 aircraft.
On successive nights.

[KMSS]

Guppy, is this the NTSB report for your engine failure?

LAX07TA208

[SNS3Guppy]

what we can say: it is technically IMPOSSIBLE to keep a tpe331 running with the prop feathered- instead of a pt6 where stopping the prop will not stop the core

This is not true.

yes, you are right, giving a briefly reverse burst after startup was a common procedure for surely removing the start locks. but we did not shut ( in everyday business) holding in reverse , just in beta taxi range, that worked. that is valid for the 4 bladed hartzell props we had installed.

You do understand that beta is everything aft of the low pitch stops, right?

Alpha range is everything forward of the low pitch stops; beta range is everything operating at a pitch less than the low pitch stops. Reverse is beta. Beta is reverse. Again, rather than cover this material again, visit http://www.pprune.org/tech-log/324680-beta-range.html

i think you incident on the dromader does not cover this- the prop did NOT feathered after loosing oil, it kept on running when i understand you right.

I'm not sure that you do. The propeller did not feather. The engine continued to run. The propeller assembly and the engine are two different systems. One can't necessarily speak in terms of an engine feathering, because it's the propeller that feathers. The propeller didn't feather, and the engine ran without oil. This thread is about low oil quantity in engines (and the procedures or lack thereof for such an eventuality), with considerable drift regarding propellers. I realize you're really hung up on the issue of propellers, but this is really about oil in engines.

Some engines that drive propellers use engine oil to operate the propeller, but some don't. Some, like the T-56 previously described (C-130) utilize hydraulic fluid in an entirely separate fluid system.

its a very interesting question : will the prop feather by alone without oil when the turbine still runs? i do not know, the checklist does not cover this. but when it does you will surely loose any engine thrust from the prop.

I really don't think you've been following this conversation very well, and I really don't think you understand the engines you operate very well, either.

Whether the propeller feathers or not is a drag issue. Not a thrust issue.

In the example previously given on the Garret motor, the propeller didn't feather. It also didn't provide any torque. Thrust is a function of torque; lose torque (because there's no oil to actuate the propeller mechanism), lose thrust. Torque is the indirect measure of thrust that we use (it's actually resistance to rotation, but for our purposes in the cockpit, we use it to equate thrust, and some garret installations actually read in horsepower, rather than torque or psi).

The engine continuing to run is really neither here nor there given the operation of the propeller; if the propeller doesn't feather, whether the engine is running like a top or not doesn't mean much to the pilot; the only issues really of concern are that A)one no longer has usable thrust, and B)one may have a significant drag issue, depending on the mechanism of operation of the propeller in use).

Thanks - It just confirms what I said about shutting the engine down with the S&F while you still have control, as either situation is rather bad.

Not necessarily. Shutting down to prevent the engine from shutting itself down is somewhat like fighting until has one bullet left so that one has something to use on one's self.

There are times when one is far better to use all the remaining thrust from the engine. Saving the engine isn't necessarily in the best interest of the pilot or aircraft.

In my case, when it was evident that I was getting no more useful torque out of the engine, and given that I had very little altitude to use, I pushed the power lever forward, in order to minimize drag with the propeller. It didn't feather, but it was the remaining option. The temperatures took off (and weren't limited, given that the engine doesn't have a limiting computer in that installation, to go back to grounded27's previous comments). I didn't shut down the engine until I came to a full stop on the mountainside. On any other motor, this wouldn't have had any impact, pushing the power lever up; on this installation it did, and was the final option available.