P3 Orion ops

[VH-XXX]

I noted that during the search efforts for MH370 the P3's shut down their inner engines presumably for loitering.

This got me thinking, what other aircraft types would be operated in this way and how normal is it to shut down multiple engines? I note that when they taxi they shut down their outer engines.

I'm not suggesting they shouldn't, I was just wondering how many aircraft would get away with this, B52 perhaps?

[tail wheel]

I remember flying in an Ansett Lockheed L188 Electra (civilian version of the P3 Orion) with the two inboard engines near idle speed. The reason was a design fault, subsequently rectified, but in the interim Electras cruised with the inboard engines at or near idle:

Three aircraft were lost in fatal accidents between February 1959 and March 1960. After the third crash the FAA limited the Electra's speed until the cause could be determined.

After an extensive investigation, two of the crashes (in September 1959 and March 1960) were found to be caused by an engine mount problem. The mounts were not strong enough to damp a phenomenon called "whirl mode flutter" (analogous to the precession of a child's top as it slows down) that affected the outboard engine nacelles. When the oscillation was transmitted to the wings and the flutter frequency decreased to a point where it was harmonic with the outer wing panels, violent up-and-down oscillation increased until the wings would tear themselves off.

[Arm out the window]

I'm no expert on the type but I was under the impression they only shut one engine down for endurance rather than two.

[VH-XXX]

You are probably correct, I was only going by a pic taken from the inside of the cabin.

I'm sure with their risk assessments and aircraft operating procedures etc they are confident that there's enough time to get the inner engine spooled up again if the outer engine fails :eek:

[fedex727]

The mighty Nimrod could also to shut down 2 engines if required, to extend the on task time. #1 Engine on the P3 is the usual choice to shut down in flight, as it does not have a generator, therefore no impact on aircraft/avionics services.

[ButFli]

Guys,

Are you sure it's an inner engine that is being shutdown? Standard procedure is to shutdown the outer left engine because it's the one without a generator. You can even shutdown both outer engines if you're keen.

As for safety, the requirement is that in the event of a failure you have to be able to restart all your (operable) engines by a given altitude AGL (3000 IIRC). There is therefore a minimum altitude AGL for 3-engine ops and a higher minimum for 2-engine ops.

This is not some dodgy thing invented by gung-ho RAAFies. It's a legit procedure in the aircraft manual.

[Arm out the window]

There would also be a certain time factor built in to allow for them finishing their frozos prior to commencing the restart checklist, which would naturally add to the minimum height requirement! :)

[Rogan82]

No1 it is usually, sometimes No 4 to bend the airframe back the other way!

A min height and speed restriction with one loitered is only required when you have a ROD on two engines at heavy weights. Once that ROD due weight is zero, game on and down you go to MOA 100'. Just don't forget to use the rudders when powering up or those frozos will end up on the floor!

[VH-XXX]

On the footage I spotted they had number 2 shut down.

[ButFli]

Can you link us, VH-XXX?

[Capt Fathom]

I noted that during the search efforts for MH370 the P3's shut down their inner engines presumably for loitering
On the footage I spotted they had number 2 shut down.


Which scenario did you see XXX ?

P3's with their Inner engines shutdown, or just one P3 with number 2 shut down?

[VH-XXX]

It was on a channel 7 news clip and showed a guy looking out the left window with a prop next to him not spinning. No idea on alt, could have been 3,000ft+ easily, lots of water so hard to tell.

The single engine shut down sounds like the most likely scenario.

I note they shut down the outer engines for taxi. Anything to rack up less hours is a good thing I guess!

[500N]

Try the Age or SMH web sites.

I watched one after the other today after watching one that was in an article,
they came on when the previous one finished.

I'll try and find them.

[ButFli]

ZmEV81f2l7Q

Have a look at this video starting around the 0:45 mark. You clearly see in the cockpit a lever pulled with a big number 1 on it to the left of 3 more levers with 2, 3 and 4 on them. Yet the view out the left window shows a prop not spinning "right next to him".

It's the outer engine. If it was the inner engine you'd see the outer engine behind it.

[onetrack]

I agree with what VH-XXX saw - I saw the same video clip, it was No.2 that was shut down on the RAAF P3.
Both the running outer engine and the stopped engine were clearly visible in the clip. I'm having trouble finding the video clip again.

[VH-XXX]

Just saw a clip on Sunrise taken from behind the left wing and engine 1 was shut down. Interesting ! The other clip of engine 2 was in front of the wing.

[EW73]

Hi guys,
Of course, thats a video of an American P3 flying over what looks like Saudi or Kuwait.
We need to be clear about a few things here with RAAF P3 operations:
1/ only engines 1 and/or 4 are ever shut down for loiter operations, which is what we are discussing here. That prop you see out the Tacco's window is engine 1.
2/ with both 1 & 4 shut down, the minimum intentional flight altitude will be 1,000 feet. The Flight Engineer would calculate the airplane performance on one engine prior to loitering on two.
3/ the video is USN, they do things sometimes differently, and in the case shown, shutting down engine 1 with the Emergency Shutdown Handle (that big black and yellow handle) is for just that, emergency shutdowns, not loiter shutdowns. Loiter shutdowns are controlled with the Feather Buttons, located overhead the Flight Engineer, slightly to his left. These buttons are used both for shutting down the engine for loiter, and restarting (unfeathering) it when required.
4/ The inboard engines are never intentionally loiter shutdown, since they both drive an active generator and one each of the air conditioning (and pressurization) compressors. Though engine 4 does have a generator, unlike engine 1, this is the third, standby generator that will cut in if there is a failure of one of the other two.
5/ For me , the complication here is that, although engine 1 does not have a generator, it is the critical engine and therefore causes some rudder and trim work for the flying pilot each time big power changes are introduced. So, with that in mind, my technique was to always loiter engine 4, which made the airplane much easier to handle during big power changes. If the generator was subsequently needed, we simply restarted engine 4 and loitered engine 1, but that was very rare.
6/ You may notice that the loitered prop is always seen in the 'X' configuration, with none of the prop blades horizontal. That is intentional, and handled by the Flight Engineer to limit the amount of turbulence off the blades affecting the closely following wing, for better ride quality.

In an emergency restart, the Flight Engineer can have the loitered engine at full power within around 20-25 seconds, I've been there!
Normally, when the intention is to fly below 100 feet, all four is good, but that will not apply to these missions! (continuous RAWS is annoying!)

I'm seeing these video shots as you are, and I'm surprised both 1 and 4 are not loitered for most of the search phase of the mission.

Top airplane . . .:ok:

[john_tullamarine]

That is intentional, and handled by the Flight Engineer to limit the amount of turbulence off the blades affecting the closely following wing, for better ride quality.

Seeing there were some comments earlier re the L188, it was a little different in that the props - quite slowly - rotate when feathered (too long ago to recall the reason) .. felt like going over a road speed hump .. at speed .. each time a blade crossed the LE .. those were wonderful days ...

[VH-XXX]

Just looked at the video above and it's clearly the outer engine shut down. The constant clips via Channel 7 literally show a prop right next to the guys head looking out the window, clearly number 2, not spinning. Very interesting.

Maybe they had an engine failure ! :bored:

PS: By starting this thread it was not meant to suggest anything dodgey has been happening; it was simply a discussion on the operations of the P3.

[The Rage]

My late dad used to fly on the malaysian PC130H. And recall him telling me that they used to shut one engine down. And they would be up there on SAR for up to 14 hours.


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[Sqwark2000]

WRT to the OP and other aircraft, we feather and shut down the No.1 engine on the taxi to the gate after landing on the ATR72. To save fuel and deplane the passengers faster.

[EW73]

With the P3, with the steps being so far aft, behind the flaps, by the time they have been lowered into position after parking, the #2 engine has almost stopped rotating because of the built-in prop brake.
This same prop brake also stops reverse rotation when the engine is shut down (loiter or emergency shutdown) in flight.

[Super Ord]

Hi Guys, I spent 4 years stooging around in P3's, and yes, typically, 90% of the time, No. 1 is shut down to loiter.


On rare occasions, No. 2 is shut down for the simple reason of not leaving a thermal "shimmer" from 2's exhaust if filming or taking photos with the main crew door open.

[Brisbane Sinner]

The engine-driven cabin environment compressors mounted to the inboard engines of the P-3 are what gives her distinctive whistling sound on the ground when compared to the C-130, which runs essentially the same engine. I've spent many hours on both the T-56A-14 and -15 and they are a superb engine - very strong and very powerful. They incorporated a very clever relationship between the typical hydromechanical fuel systems of the day and the beginnings of an 'electronic' exhaust temperature controlling/limiting system. There was much to learn about what happened and when for any movement of the power levers by the crew.
The industrial turboshaft version of the T-56/501 would churn out 8000+ horsepower for months on end if needed.
With regard to the loiter mode, an outboard engine shutdown wasn't always available to the crew depending on where the task took the aircraft and what the possible consequences were of an unsuccessful restart prior to recovery.

[dostum]

Memories....
Normally no1 (the far left) is loitered because there is no generator on that engine. Loiter will save a lot of gas and give you about 1 more hour onsta. It is because the other engines are now running hotter (more efficiently) to obtain the same loiter IAS. The big problem was a lot of rudder required to balance with high power on the other engines. That's one of the reasons I tried to avoid loitering. You would shut down no 4 to really prolong time onstation, but the risk is you are now down to 2 generators. And you can't do this until you have burned off significant fuel.

During the current SAR, I can't imagine the p3 crews would have loitered in the initial search areas far to the southwest. You need to account for the possibility that the engine won't restart, and that you might be restricted to 10000' due loss of pressurisation (3 engine 10 config). An unlikely scenario, but that was SOP back in the day.

[Neptunus Rex]

Having flown both the Orion (P3B and P3C) as well as the Nimrod, I can verify that one or both outboard engines were regularly shut down to improve endurance.

In the case of the Nimrod, the Flight Engineer would calculate 'Crit Weight' before the second Spey was shut down. He would also write the Min Drag Speed on a placard for the pilots, who would ensure that the aircraft was flown with a safe margin above that speed. Should one of the running inboards fail, selection of full power on the remaining engine would guarantee a minimum rate of climb of 200 feet per minute whilst the first outboard was relit.

I have shut down engines in flight on hundreds of occasions and not once was there the slightest problem restarting them.

Is it not ironic that the Nirod was the only Long Range Maritime Patrol aircraft to have an in-flight refuelling capability, which would have been of tremendous value in the present search.

[EW73]

dostum . . . what you talkin 'bout son?

Percieved restarting problems of a serviceable engine were never a consideration when faced with long onstation times.
The only prior problem that would prevent a loiter shutdown was the lack of a successful pre-shutdown inflight 'NTS' check (Negative Torque System), a check of the automatic prop protection system that prevented the propellor from driving the engine beyond certain limits. If that doesn't check out just prior to shutdown, then the engine will be kept running, though still capable of emergency shutdowns.

I can't recall ever not loitering an engine because 'it may not restart'. Simples, if it doesn't restart, we go to the 'nearest suitable airport' and land, and that's not even classed as an emergency!

[dostum]

Yes I haven't flown the P3 for many years! What I probably should have said was this: given the short period of time on station, due to a four hour transit both ways I doubt it would have been worth doing the loiter shut down.

I have actually had two restarts that did not work properly. On one occasion the NTS INOP light illuminated after flteng pulled out on the fx button. The engine was secured with the e handle. On the second occasion, the fx button light remained on after PCO was released. Luckily we were within a couple of hundred miles of home plate both times.

I would not want this to happen 1000nm from nearest suitable (as in op southern Ocean rescue).

Cheers

[EW73]

Cheers mate no problem.....

You probably remember the RPM racing up to around 70% with a heap of induced yaw, before the NTS INOP light actually come on!

Normally VERY reliable, great airplane!