P3 Orion ops
Join Date: Jun 2010
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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.
This same prop brake also stops reverse rotation when the engine is shut down (loiter or emergency shutdown) in flight.
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.
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.
Join Date: Apr 2014
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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.
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.
Join Date: Nov 2007
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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.
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.
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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.
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.
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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!
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!
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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
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
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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!
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!
