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? For Pilots Of 4 Engined Aircraft  
User currently offlineUndies737 From Australia, joined Aug 2003, 58 posts, RR: 0
Posted (9 years 7 months 1 week 2 days 7 hours ago) and read 4511 times:

a question i have never got around to asking our pilots, during the last 4 years i've been maintaining 4 engined aircraft...

i am aware that during your aircraft conversion course (type rating), you are trained to handle the aircraft in most abnormal flight conditions.
with how many engines inoperative at any one time do you routinely practice? 1,2, maybe 3 in worse case scenario?

i have encountered 1 and only occasion.
enroute; malaysia-darwin where an engine (#2eng) was shut down. after i discussed with the loadie & captain how minor that "visible fluid leak" was, it was shut down in accordance with company policy and diverted to bali.
i thought nothing of it but there were many blank looking faces (infantry soldiers do have fears too). like the typical general public, they thought the worst when 1 of 4 eng was shut down in flight.

the term "loiter shut down", i have heard of it but cannot imagine shutting down an engine in flight to save fuel, after all a plane's performance and fuel economy is designed to be at its best when all engines are operating?
correct me if i'm wrong

thanx for any feedbacks

undies737

13 replies: All unread, jump to last
 
User currently offlineStarlionblue From Greenland, joined Feb 2004, 17056 posts, RR: 67
Reply 1, posted (9 years 7 months 1 week 2 days 7 hours ago) and read 4481 times:

A 4 engined aircraft with 3 inop engines will not be able to maintain altitude.

A one engine out scenario during the takeoff roll after V1 is the worst case engine out scenario, whether the plane has 2, 3 or 4 engines. If one more engine should shut down on a quad, IIRC the certification rules state that the (comercial) plane needs to maintain altitude, and this is a problem is you are on the runway on your way into the lights. So even if two engines out are worse than one, your options just went from some to "absolutely nothing I can do". If you are at altitude, your options are of course better.

1 engine is routinely practiced. If 2 engines out on a quad are I do not know.


"Loiter shut down". As you say, quads are built to cruise most economically with four engines turning. The exception is certain long range patrol aircraft like the Orion that gain more range at moderate speeds with two engines shut down.



"There are no stupid questions, but there are a lot of inquisitive idiots."
User currently offlinePihero From France, joined Jan 2005, 4533 posts, RR: 76
Reply 2, posted (9 years 7 months 1 week 2 days 3 hours ago) and read 4440 times:
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Undies737,StarlionBlue,

Yes,airlines do routinely train for engine failures.

The engine failure at V1 is part of the JAR andFAR requirements.
The cruise single and double failures are generally part of a loft training.
The triple failure scenario involves a light airplane,close to an airfield, therefore a very quick fuel dumping reaction from the crew is required as well as a continuous descent into landing as the altitude capability is severely reduced.
A very sporty proposition as the dissymetry is drastic,the approach speed very high, and the flight control situation could be difficult,depending on which engine is left ,whether the APU could be made available and so on...



Contrail designer
User currently offlinePhilSquares From , joined Dec 1969, posts, RR:
Reply 3, posted (9 years 7 months 1 week 2 days 1 hour ago) and read 4414 times:

On the 744 a two engine approach and landing is required on every 6 month check. In addition to that, a 3 engine approach to a landing and a go around is also required.

On the 744/747 the APU isn't available for start in flight.

Depending on the gross weight and altitude the 744 can maintain the same flight level. But generally speaking, you are going to have to do a driftdown. Several techniques are available for that, but you would descent down to your optimum 3 engine altitude. On a 3/4 engine aircraft you can certainly continue to your destination. The FARs and JARs don't require a divert as they do in a two engine aircraft.

Flying a two or three engine approach is really no big deal. There is some asymmetrical thrust issues but it is very controllable with rudder. The worst case would be a go around at light gross weight. The 744 is very stable at high gross weights and actually easier to fly. (personal opinion).


User currently offlineLeanOfPeak From United States of America, joined Oct 2004, 509 posts, RR: 1
Reply 4, posted (9 years 7 months 1 week 2 days 1 hour ago) and read 4397 times:

The difference between the loiter shut-down scenario and an unplanned shutdown in cruise is twofold.

1) The altitude is set by the mission, i.e. electronic reconnaissance, subchasing, or SAR, so the aircraft is not flying at optimal cruise altitude regardless of the number of engines in operation. Engines derate with altitude, which is why you can run all the engines at a high power setting at altitude. When the aircraft is being operated at low altitude, there is considerably more power available, and, since the engines generally operate more efficiently at wide open throttle, it reduces fuel flow in specific circumstances to run half the engines wide open compared to running all the engines "half open."

2) Loiter means loiter. Optimal endurance is achieved at a lower speed than optimal range and is optimized differently.


User currently offlineUndies737 From Australia, joined Aug 2003, 58 posts, RR: 0
Reply 5, posted (9 years 7 months 1 week 1 day 19 hours ago) and read 4322 times:

thanx everyone for all your informative feedback.

having only a student pilot licence, all my 4 engine experience came from flying the C130J,B707 simulators i have at work. whenever i get a chance for a play, i usually make a point of practicing assymetrics with an outboard engine out or even 1 outboard & 1 inboard (1&3 or 2&4) inoperative.

got any pointers/tips?  Big grin

dave


User currently offlineRaggi From Norway, joined Oct 2000, 1001 posts, RR: 1
Reply 6, posted (9 years 7 months 1 week 18 hours ago) and read 4099 times:

Quoting PhilSquares (reply 3):
Flying a two or three engine approach is really no big deal. There is some asymmetrical thrust issues but it is very controllable with rudder.



If on a quad you lose both engines on one side, is this statement still true? Which engines are normally simulated out on training? I remember my groundschool teacher told me stories from training when he flew the C141, and losing engines 1 and 2, or 3 and 4 was apparently a "big deal"...

raggi



Stick & Rudder
User currently offlinePhilsquares From , joined Dec 1969, posts, RR:
Reply 7, posted (9 years 7 months 1 week 8 hours ago) and read 4038 times:

On the 744, there is no real "critical" engine side. Although, having the upwind side with the engines does make is slightly more challenging, but it's no where near being a big deal.

User currently offlineLyzzard From Singapore, joined Nov 2003, 404 posts, RR: 14
Reply 8, posted (9 years 7 months 5 days 7 hours ago) and read 3823 times:

All engine flame out scenarios are often practiced during conversion training. This is a possible occurence should an aircraft encounter flight into an area of volcanic ash.

And in addition to 2 engine approaches (on a 4 holer), 2 engine go-arounds are sometimes practiced too. It's quite a dicey maneouver but is possible with practice.

I'm not sure of the term "loiter shutdown". Perhaps the only instance, which I can think of, in which an engine would be intentionally shutdown would be on the taxy segment. Oftentimes, company procedures might allow 3 engine taxi (on a 4 holer) in order to save fuel in case of a long taxi route or delays.


User currently offlineLeanOfPeak From United States of America, joined Oct 2004, 509 posts, RR: 1
Reply 9, posted (9 years 7 months 5 days 1 hour ago) and read 3740 times:

Loiter shutdown is not generally referring to a civil operation. I know it was done in PBY's doing low-level missions in WWII. I also believe it has been done more recently in P-3's.

User currently offline411A From United States of America, joined Nov 2001, 1826 posts, RR: 8
Reply 10, posted (9 years 7 months 4 days 20 hours ago) and read 3692 times:

Some years ago DanAir, when they were operating deHavilland Comet 4 aircraft, applied to the UK CAA to be able to shut down one engine in cruising flight, so as to improve operating economics....the Comet 4 being somewhat overpowered as it was.
The CAA replied...absolutely NOT. And, so they should have.
A daft idea, for civil ops.
Military ops, on the other hand, are a different kettle of fish.


User currently offlineUndies737 From Australia, joined Aug 2003, 58 posts, RR: 0
Reply 11, posted (9 years 7 months 3 days 8 hours ago) and read 3556 times:

Yesterday, I had the opportunity of doing some asymmetrics 800ft over Hong Kong in a B707 sim (#3,4 out). Directional control is not much of a problem at 290KIAS & the instructor restored pwr on #3,4 soon as I picked up the dead wing.

Another question I have; what type of "run up" checks are done on a turbofan/jet before takeoff.
is there a reason I've never heard a jet spool up for such pre-takeoff checks. whereas a piston will have a mag check & turboprops have a prop overspeed governer check.

thanx again for all the insight

Is there any a.netters from australia (sydney) who could show me through some widebody Boeing/Airbus simulators, please drop me a line.

undies737.
707greasemonkey


User currently offlineSQ325 From Germany, joined Jul 2001, 1451 posts, RR: 7
Reply 12, posted (9 years 7 months 2 days ago) and read 3474 times:

Hey

On the RJ85 we do 2 engine approaches landings and go arounds every 6 month!
We also simulate a double engine failure shortly after V1 especialy in airfields like florence this is a pretty tough thing!
If we have a flame out on one engine we don't even declare emergency!
And we can maintain a safe altitude with 3 engines and also with 2 engines!


User currently offlineJ32driver From United States of America, joined May 2000, 399 posts, RR: 1
Reply 13, posted (9 years 6 months 3 weeks 5 days 1 hour ago) and read 3266 times:

Flew the 146 for a while. Every sim ride we saw a V1 cut, bring it back around for an approach, go missed, lose the 2nd engine as you shoved up the power for the missed approach. Then flew 2 approaches on 2 engines only (either 1 &2, or 3&4).

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