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prop low oil light


rami
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Our books say light ON, RPM within limits Shutdown.

Why? Fluid is present prop is regulating speed normally so fluid should be avalible to feather. You shutdown do to the Low fluid level and the LARGE fluid requirement to break and retract the low pitch stop, and the large blade angle change to go from 23 degrees to full reverse if selected. A low fluid stste would cause delays in this movement and controlability issues.

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Been many years for me but it seems to me that with a prop low oil light, that unless you really need the engine, you cage it. Sure RPM might be stable now but what happens when it's not? Are you hoping that when the RPM starts fluxing, etc., that you have enough fluid left to feather the prop or are you just hoping that the prop will overspeed and pitchlock? Remember that no matter what the -1 says, common sense usually prevails and will probably save your butt, the bird, and the rest of the crew.

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Our FM stated:

If light “ON†and RPM within limits, continued operation is permissible.

Permissible !!! It doesn’t say to continue operation!!!

And on the first “NOTEâ€:

Continued operation with an actual low propeller oil condition will require a propeller oil leakage inspection.

It doesn’t say what to do if there is a miner leak???

Followed by a second “NOTEâ€

Landing Traffic pattern shutdown of an engine with a propeller malfunction is usually desirable.

Usually desirable!!!! It doesn’t say recommended!!!

So the “book†seems indirectly suspended the action to our experience.

As a flight engineer I am following this:

1- If light ON with no evidence of abnormality in RPM or prop leak, I will advise to land with the engine running with a note to the captain to avoid as possible using the effected engine in reverse.

2- If light ON with miner leak, I will advise to continue using the engine until RPM starts giving any abnormal signs, then if condition permits to fly with 3 engines; I will advise to shutdown the engine. If condition is critical with 3 engines, I will advise to use the engine under pitch lock propeller operation procedures, until the before landing then engine will be shutdown.

3- If light ON with heavy leak, even with RPM normal, I will advise to shutdown the engine at the time, unless condition is critical with 3 engines, then the engine will be used under pitch lock propeller operation procedures, until before landing then engine will be shutdown.

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What if the major oil leak is on the unseen outboard side of the engine? During a training mission at the Rock while I was in the 16th, I was flying with 2 students pilots and this arrogant IP major who thought he knew anything about everything. We got a prop low oil light. He said he was going to unscrew it and ignore it. I leaned over and told him that if he didn't turn this bird around and head back to LRF, cage the engine before landing, that i'd put in a hazard report to the safety office and then see where his pending assignment to the 89th Wing in DC ended up. He made some self-saving explanation to the students and he followed my "recommendation."

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SEFEGeorge;

Are you calling for “caging†any engine with prop low oil light Regardless of any other indication, location or situation?

Don't recall saying "regardless." Over the pond, would take other factors into the decision. Over land, no other issues, engines shut down, etc., I probably would recommend caging it and land.

If you're relying on a prop low oil indication problem, and not a leak on the outboard side of engine or another problem, you're waiting for another indication from the ending/prop before you choose. As reliable as the Herc is, you're depending on the pitchlock, low pitch stop, etc., to do their jobs. They probably will. But why take the chance?

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  • 2 weeks later...

1- If light ON with no evidence of abnormality in RPM or prop leak, I will advise to land with the engine running with a note to the captain to avoid as possible using the effected engine in reverse.

The problem I find with this ideology is you are working with an "unknown" situation.

Prop oil can leak on the far side of the nacelle where you can't see it

OR if your rear lip seal blows it will dump into the pan under the gearbox and drain out back on the engine where you would'nt assosiate it with a prop leak. (you know that the rear lip seal is the PRESSURIZED sump, not the atmospheric sump. For some reason it seems logical to think of it the other way - atmospheric to the rear, but that's wrong.

If you blow you pressurized sump seal its going to be a bad day.

I have had low oil lights, pitchlocked props, low pitch stops fail to retract, underspeeds, overspeeds and just about every other bad day item in the book. That prop is very reliable but it can also munch your butt for dinner if it wants to.

The main point of my rambling post here is you are honestly operating with an unknown condition, what if your problem.

What would happen is just as the pilot is going into the landing flair and all of a sudden there isn't enough fluid to operate the piston and the prop goes to a really nice flat 23 degrees, that could very possibly cartwheel you down the runway.

Thats why I would ALWAYS demand the pilot to shut it down before landing, you dont fool with props if you want to live to be old and crippled like me and thats why the operating manual recommends shutting it down before landing. If you pilot cant land on 3 engines in this plane he needs more sim time, the bird fly's great on three.

Cruise is a different story, depending on the mission, whether its a critical "operation" or just hauling trash would help me in my decision to recommend the pilot to keep it running or shut it down.

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I can understand the point you are trying to make, but a lot about this isn't accurate. The pressurized sump is to the rear, not the atmospheric, but the rear lip seal itself is in fact an atmospheric seal. Many people get confused with this because the prop shaft seal, a pressurized seal, is in the same area, and it's leak is indistinguishable from a rear lip seal while the propeller is installed. Many propellers get removed for rear lip seal leaks, only to be found not leaking in Back Shop. These leaks are normally caused by the prop shaft seal, which are changed during prop installation anyway, and usually makes the flightline workers look dumb to the back shop workers who don't even mess with the prop shaft seals.

The easiest way to distinguish between a rear lip seal leak and prop shaft seal leak is pay attention to when it leaks. Prop shaft seals leak while the system is pressurized, either while running or when blade angle changes are made statically. Rear lip seal leaks usually occur after the aux pump stops running during static blade angle changes as the atmospheric sump temporarily pressurizes and starts venting pressure out of the valve housing cover breather.

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It takes a lot of fluid loss to cripple a prop. If you start out with a fully service prop, you will lave to lose 3 and a half quarts to get a prop low oil light. At that point, you'd have to lose another 3 and a half quarts to have an empty pressurized sump. The amount of time spent spent going from full to pitchlocked prop depends on leak rate, and if the leak rate on the right wing is small enough that the gearbox scupper and contain it and drain it out invisibly can be a long one.

A dangerous leak will be visible unless it goes down the propeller shaft, and an observant crew will see the gallon increase in oil quantity.

Anyone know of a crew that experienced a pitchlock caused by actual prop leakage? If seen it from malfunctioning pitchlock regualators and blown quad seals (resulting in excessive RPM), but never from an external leak.

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Our FM stated:

If light “ON†and RPM within limits, continued operation is permissible.

Permissible !!! It doesn’t say to continue operation!!!

And on the first “NOTEâ€:

Continued operation with an actual low propeller oil condition will require a propeller oil leakage inspection.

It doesn’t say what to do if there is a miner leak???

Followed by a second “NOTEâ€

Landing Traffic pattern shutdown of an engine with a propeller malfunction is usually desirable.

Usually desirable!!!! It doesn’t say recommended!!!

So the “book†seems indirectly suspended the action to our experience.

As a flight engineer I am following this:

1- If light ON with no evidence of abnormality in RPM or prop leak, I will advise to land with the engine running with a note to the captain to avoid as possible using the effected engine in reverse.

2- If light ON with miner leak, I will advise to continue using the engine until RPM starts giving any abnormal signs, then if condition permits to fly with 3 engines; I will advise to shutdown the engine. If condition is critical with 3 engines, I will advise to use the engine under pitch lock propeller operation procedures, until the before landing then engine will be shutdown.

3- If light ON with heavy leak, even with RPM normal, I will advise to shutdown the engine at the time, unless condition is critical with 3 engines, then the engine will be used under pitch lock propeller operation procedures, until before landing then engine will be shutdown.

I was a "Captain" more years than I care to remember, and I'm definitely with tenten on this...good advice.

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It takes a lot of fluid loss to cripple a prop. If you start out with a fully service prop, you will lave to lose 3 and a half quarts to get a prop low oil light. At that point, you'd have to lose another 3 and a half quarts to have an empty pressurized sump. The amount of time spent spent going from full to pitchlocked prop depends on leak rate, and if the leak rate on the right wing is small enough that the gearbox scupper and contain it and drain it out invisibly can be a long one.

A dangerous leak will be visible unless it goes down the propeller shaft, and an observant crew will see the gallon increase in oil quantity.

Anyone know of a crew that experienced a pitchlock caused by actual prop leakage? If seen it from malfunctioning pitchlock regualators and blown quad seals (resulting in excessive RPM), but never from an external leak.

Thats right. Exactly.

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Head I win; Tail you loss. “Deal†?

With honesty my younger brother used to say: “Dealâ€. I spin the coin with confidence.

I never loss!!!

Fellows, this is the role of the game set by Flight Manual in this topic.

Quoting role 1:

If light “ON†and RPM within limits, continued operation is permissible.

Quoting role 2:

Landing Traffic pattern shutdown of an engine with a propeller malfunction is usually desirable.

“FM†will never loss.

So; we are lift with system knowledge and common sense to this subject.

My Knowledge and common sense sets the following for “me†to advice to land with 4 engines (if no evidence of abnormality in RPM or prop leak is detected):

1- Landing with 4 engines is safer than 3 engines. (In some cases “Left Seat Issue†is involved)

My authority to land with 4 engines is (FM role 1).

2- Drop of hydraulic level gradually is the common behaviour of the 54H-60-xxx prop. (Experience)

3- Gradual drop of level will lead to the following time gap/antiviral subsequence: light ON, RPM unstable (beating noise), prop pichlocked, prop fail to feather.

4- Landing with one prop windmilling -due to fail to feather- is one of the worst scenario ;( countless aircraft landed safe with prop windmilling).

5- Heavy and sudden loss of hydraulic fluid -from the inside or outside of the engine will pitch lock my prop at the time, and will put me-sooner or later- on landing with a windmilling propeller.

6- Level switch malfunction is a common fault of the 54H-60-xxx propeller.

Quoting “Danâ€:

What would happen is just as the pilot is going into the landing flair and all of a sudden there isn't enough fluid to operate the piston and the prop goes to a really nice flat 23 degrees, that could very possibly cartwheel you down the runway.

Dan, I need more detail on this.

My understanding that all the prop during the flair is resting on around the 23 degrees angles (low pitch stop protection).

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  • 2 weeks later...

if prop low oil light came on and all indication normal

1.what the action

2.we have to shutdown the engine prior to land

Not to sure if this helps or not but also an action that can be taken is condition lever to AirStart.

If light stays on condition indicates low oil or indication failure.

If light goes out condition indicates a posable main pump failure in the Pump housing.

AJ

Note: Techo's prospective as for shutting down I guess what ever is in the section 3 of the flight manual is the way to go.

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Books tell you to shut the engine down and make sure you cage the correct Engine, i have seen a prop light bright and steady for over 25 minutes and the FE asked me what i thought about it and it had been on for about 10 minutes and he had already swapped indicators on GB Oi Pressure which told me he knew it was not an indication issue as he had no gear box oil pressure! I told him to cage it as we were 1/2 way to Goose Bay and it took him another 15 to 18 minutes to cage the engine but the Engine did a big lunge and that prompted him to finally cage the Engine! We were all lucky the prop was not in our laps in pieces! Funny thing this FE was a Instructor FE at LR and all i did was shake my head and pray! -1 Says shut it down and why play with fire, it could cause you an issue with the prop not going to feather which at altitude would not be good depending on your GW!

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I don't know how I would handle this situation, given the idiotic prop oil level indication system. But, when the HC-130 was originally introduced, it was thought that the aircraft would fly to the search area, then run on two engines to allow loitering time. Does this sound like a good idea????

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My understanding was that how the Coasties do/did their searches. Cruise engine shut down 2 engines and loiter for a long time. Could prove exciting if one engine all of a sudden gave up the ghost. But I also understood that all that needed to be done was take the condition lever to airstart on the others.

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I don't know how I would handle this situation, given the idiotic prop oil level indication system. But, when the HC-130 was originally introduced, it was thought that the aircraft would fly to the search area, then run on two engines to allow loitering time. Does this sound like a good idea????

At least as good as flying a B-25 or goonybird or 123 out over the water, and have to assume that an active SAR is not some frivolous joyride...

My $0.02

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  • 2 weeks later...

My understanding was that how the Coasties do/did their searches. Cruise engine shut down 2 engines and loiter for a long time. Could prove exciting if one engine all of a sudden gave up the ghost. But I also understood that all that needed to be done was take the condition lever to airstart on the others.

We have that blerb in the herk book too that says flaps up endurance may be increased by shutting down one or two engines.

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That is what we used to do. Still do in some extreme cases. BUT, part of the process is, after cruise engine shutdown, you set everything up for air start (including NTS checks prior to shutdown), that way if anything exciting happens, push it into air start and hopefully you get the fan back. I've been out of the flight deck for awhile now so if I missed something...

I remember one pilot would show young(er) copilots that with two shut down and 1 in flight idle, you could still maintain straight and level flight for a while you sorted out the mess that got in you in that predicament...

Hell, flying around for 8-12 hours looking at water, you got to know this bird, we played "what-if" a lot...

Senior

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I think that one engine at power, one at flight idle, with the other two caged, ended up in the AC syllabus. They were doing it in 2005. A real eye opener.

One or two engine shutdowns were a big help with the B models. Not used so much when externals arrived on the H models. Normal ops in the P-3 world. With the outboards standing tall, the long search was much less boring for the FE!

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