Multiple engine failures

[FlyingForFun]

I was reading this thread (http://www.pprune.com/forums/showthread.php?s=&threadid=110588), specifically the quote that "SHT8V then came back and updated ATC that they had hade multiple surges (at least 3) on the number two engine and a surge on the number one engine. Engines were now stable at flight idle in the descent and requested an expeditious approach, such that should the worst happen, would provide best possible chances of a glide in." I got thinking about engine failures on multi-engined aircraft.

What are the most common causes of in-flight engine failure? I'm talking about all types of aircraft here, from Seneca to 747. How many of these are likely to affect more than one engine? A couple of obvious causes I can think of are fuel problems (contamination, starvtion, incorrect planning), and mulitple bird strikes (such as flying through a flock of birds).

These problems that affect multiple engines - are they sufficiently common, compared to problems affecting a single engine, to support an argument that multi-engine pilots should practice forced landings in the same way as single-engine pilots do? Do any multi-engine pilots do PFLs on a regular basis?

(I am not talking about the poor performance of the typical light twin here, and the probable need to execute a forced landing after an engine failure because the remaining engine can't keep the aircraft airborne - that's an entirely different issue, and one we've discussed many times!)

I have no idea what the answers to these questions are. Any thoughts/opinions/facts would be welcomed!

FFF
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[alf5071h]

Data from PSM+ICR Project Report; note scant turboprop data - few FDRs / crew survivors.

Turbofan Symptom (Accident and Incidents) Percent of total (79 events)
Compressor stall/surge 63
Power loss 14
Stuck throttle (throttle remains fixed) 6
Fire warning 5
No response to commanded power 3
EGT warning light 1
Low oil quantity 1
Severe vibrations & perceived power loss 1
Suspected power loss due to airplane deceleration 1
Temporary power loss due standing rwy water ingestion 1
Thrust reverser “Unlock” light on 1
Thrust reverser did not transition to “Rev Thrust” 1
Thrust reverser to “Unlock” position, no power increase 1

Turbofan Symptom (Accidents Only) Percent
Compressor stall/surge 53
Power loss 16
Stuck throttle (throttle remains fixed) 6
Fire warning 6
Suspected power loss due to airplane deceleration 6
EGT warning light 3
Low oil quantity 3
Temporary power loss - standing runway water ingestion 3
Thrust reverser did not transition to “Rev Thrust” 3

Multiple events Totals
Continuous surging of multiple engines 2
Shutdown of a good engine 1
Birds 2?

Turboprop Failures Totals
Failed 45
Shut down by crew 13
Brought to flight idle 9
Other 9

Multiple events Total
Shutdown of a good engine 3 out of 13 above

[lomapaseo]

Multiple engine powerloss affecting flight are rare but documented in the FAA sponsored CAAM report (FAA NE region Powerplants/Standards).

Yes as stated above birds/ice/volcanic ash and of course the ubiquotous fuel starvation are the major causes.

The surge alone cited earlier is symptomatic of a temporary malfunction where normal flight with no more than one engine at reduced power is typical. Multiple engine surges where multiple engines stay affected (with nothing else wrong) is indeed extremely rare..

The historical occurrence of multiple engine out and an expectation of ditching is about 1 per year.

You decide if that is enough priority to add to a training syllabus.

The PSM+ICR study would suggest putting your powerplant training emphasis elsewhere

[Cougar]

Yes, birdstrike fuel problems would be the major concerns. I personally reckon that the only time i am likely to lose two engines on one side at rotate (4 engine a/c) is due to a multiple birdstrike, and this is the worst case we practice for.

As for PFL's 1) there is no data from the aircraft producer or in fact from any operator of my type in PFL's, nor glide performance in the landing configuration so speed for a glide would be guessing 2) as Loma stated, there is a greater risk of other things happening which take training precedence.

Cheers

[Tinstaafl]

Speed can be found easily enough: Vmin drag. If not published then best range speed is a good choice.

Once in a while on an empty sector I'll give myself a glide approach & landing for practice.

[Volume]

Don´t forget manufacturing/maintenance errors as sources for multiple engine failure.
05.05.1983, Eastern L1011, Miami FL : missed O-Ring seals on the magnetic plugs of all tree engines after scheduled inspection, resulting in all three of them to fail inflight !
25.08.2001, Air Transat A330, complete loss of fuel due to a fuel line and hydraulic line chaffing, causing a fuel leak. Impropper installation of the parts.

[FlyingForFun]

Seems like the conclusion is that I'm right to think that the possibility needs to be considered - but once it is considered, the statistics show that it's sufficiently unlikely not to worry about. Thanks!

FFF
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[ferrydude]

ALL MAINTENANCE RELATED;

An L-1011 descending into Nassau, The Bahamas, lost oil pressure in engine no. 2. The flight crew shut down the engine and diverted back to Miami, Florida. On the return to Miami, engines no. 1 and no. 3 shut down. At 3,800 ft above the ocean, the crew recovered engine no. 2. The flight crew then completed a single-engine landing at Miami. The O-ring seals on the master chip detectors for each engine were missing, causing engine oil loss.

A 747-200 approaching Rome made a two-engine landing after two of the four engines were shut down because of a lack of oil. Both oil filters were found to have been improperly installed.

The engines on a 747-100 taking off from San Francisco failed to develop sufficient r/min, prompting the flight crew to perform a refused takeoff. Subsequent investigation at the gate discovered power stops on the throttles used during a maintenance check. These power stops inhibited the engines from achieving their takeoff thrust.

On a BAe-146, a low-oil warning on one engine prompted the crew to shut down the engine. Low-oil warnings then occurred on two additional engines, which were reduced to idle. The crew increased thrust on the remaining engine and diverted to the nearest airport. Inspection of the engines discovered that three of the four engines did not have seals on their chip detectors and that oil leaked from the engines. The airplane had just completed a shop visit and was returning to its home airport.

A 737-400 made an emergency landing after low-oil warnings occurred on both engines during climb. Investigation revealed that the hand-crank cover assemblies on both engines were missing from the engine gearboxes, allowing oil to leak.

During descent on a 747-100, engine no. 2 was shut down because of oil loss, and engine no. 3 was shut down for the same reason eight minutes before landing. Investigation revealed the improper installation of the centrifugal oil filter retaining rings in both engines.

[BlueEagle]

On a four engine jet if either #2 or #3 disintegrate explosively then there is a strong chance debris will be ingested by #1/#4 and this will result on two out on the same side. Two out on the same side is an exercise practised every six months in the SIM in most airlines.

[Dave Gittins]

..... and isn't that exactly what happened to an El-Al cargo 747 at Amsterdam that ended up crashing into a block of flats after an uncontained on one donk which took out a second ???

I recall reading the full report on the BMI 737 that took off from East Midlands and glided into Luton. Wasn't a recommendation that only one engine at a time should have minor maintenance done without at laest one sector in between. In that case it was a boroscope check but both were done on the same night.

Has that been implemented ???

[lomapaseo]

On a four engine jet if either #2 or #3 disintegrate explosively then there is a strong chance debris will be ingested by #1/#4 and this will result on two out on the same side. Two out on the same side is an exercise practised every six months in the SIM in most airlines.

Well with 35 years of experience with the B747 and then add in the A340 for all the explosive disintegrations on # 2 & 3 there has been no more than 1 or 2 events that resulted in a permanent loss of thrust to an outboard engine.

The majority of the events were no more than minor FOD sucked into the inlet from the exploding engine.

Of course ElAL doesn't count becuase no exposive diintegrations occured to the engines.

However bird ingestion on two on one side is a much more common event, albeit still rare as a powerloss on both.

[alf5071h]

Don’t fly so high Blue Eagle; your description of explosive disintegration and subsequent damage to adjacent engines is pushing the probabilities a bit far; although as with all probability and risk it does not mean that such and event cannot happen.

I deduce that your explosive disintegration is the ‘uncontained failure’ defined in certification. This requires that uncontained engine failures should be remote ocurrences; then and if parts do let go they should be bounded in a predetermined debris zone that does not contain vital components i.e. critical part of another engine. Thus the overall probability of the loss of the second engine from the first uncontained failure is extremely remote and not worth the training time. However it is still worth training the two engines out case, particularly for birds as indicated by Cougar – the certification authorities haven’t as yet managed to regulate birds!

Thus training should be biased more towards assessing coincident hazards of airframe or system damage and dealing with these problems with the flight deck filling with ‘fowl’ burnt chicken smell and smoke (for those who use engine air on take off).

Dave G; One of the 747 engines came off due to an attachment failure.
Re UK CAA action see FODCOM http://www.caa.co.uk/docs/33/FOD199807.pdf this also refers to Airworthiness Notice, No. 72, but I cannot find a link.

Note increased number of bird strikes in low vis conditions:- most birds are not IFR qualified, thus there are many ‘terrain following’ at low altitude and the others are ‘holding’ just on top of the first cloud layer.

[BlueEagle]

My thanks to lomapaseo and alf5071h for pointing out that the scenario I quoted isn't backed up by statistics and the possibility of ingesting debris from another engine should be designed out anyway!:ok:

Fortunately none of the engine failures I have experienced were the 'uncontained failure' case so I was going on what I had heard rather than experienced.

One point I was making was that two engines out on the same side is a very regular exercise in the SIM for four engine aircraft, think I got that bit right!

[GotTheTshirt]

Explosive disintregration is what certification calls uncontained failure.
Any failure of the engine be it operational ( Bird strike - FOD ingestion) of Mechnaical ( internal failure ) is supposed to be contained within the engine. Unless you shroud the whole engine in some bullet proof material almost impossible. Main emphasis is on the hot section to contain liberated blades as these are under the highest temps/loads.

The Continental DC10 in the Mid west ( 1970's) had a fan blade get annoyed and left its mates in a hurry at 30,000 feet. The rest of the blades being union followed suit with blades everywhere. One blade left the No3 engine proceeded at high speed under the fuselage and hit the No 1 engine taking it out. Other blades hit the fuselage some near to the No2 intake but did not go into the engine. One blade hit a window near the rear on the right side and the guy in that seat left in a hurry.

Also there have been at least 2 incidents on B707 where the No4 engine failed big time to the point where it left the wing and charged into the inboard engine and the pair were last seen heading earthwards. The last one was an African aircraft, and the crew did a good job of landing in Istres in France.

Keep practicing the 2 out on one side lads;)

[Capt Pit Bull]

On the slightly smaller side IIRC there was a Navajo flying over East Anglia that 1 engine come apart pretty catastrophically, and a prop blade passed through the fuselage and took out the other engine.

CPB

[RatherBeFlying]

There was also a DC-6 (or 7) in the Los Angeles area that threw a prop blade through the fuselage from #3 to #2 or the other way around.

Landing at conveniently located runway aborted when no hydraulics for braking, but did not do well at attempted landing in golf course:(

[lomapaseo]

Explosive disintregration is what certification calls uncontained failure.
Any failure of the engine be it operational ( Bird strike - FOD ingestion) of Mechnaical ( internal failure ) is supposed to be contained within the engine. Unless you shroud the whole engine in some bullet proof material almost impossible. Main emphasis is on the hot section to contain liberated blades as these are under the highest temps/loads.

The Continental DC10 in the Mid west ( 1970's) had a fan blade get annoyed and left its mates in a hurry at 30,000 feet. The rest of the blades being union followed suit with blades everywhere. One blade left the No3 engine proceeded at high speed under the fuselage and hit the No 1 engine taking it out. Other blades hit the fuselage some near to the No2 intake but did not go into the engine. One blade hit a window near the rear on the right side and the guy in that seat left in a hurry.

Also there have been at least 2 incidents on B707 where the No4 engine failed big time to the point where it left the wing and charged into the inboard engine and the pair were last seen heading earthwards. The last one was an African aircraft, and the crew did a good job of landing in Istres in France.

Keep practicing the 2 out on one side lads

I have no problem with the opinion bolded above

However a few facts need to be straightened out.

any failure is supposed to be contained is not a regulatory requirement simply becaue it isn't practical. The regulations call for only a prescribed level of containment (typically that of a single fan blade release which is at a much higher load than any turbine blade).


It wasn't Continental DC10 it was National Airlines. The blade that hit the # 1 engine on the other side of the fuselage, did not initially disable the engine but did cause an oil leak which eventually depleted the oil as the engine continued running through the landing. The window that was hit (only one) was in front of the wing and not at the rear of the aircraft.

The (3) 707 incidents did not involve # 4 failing and striking the # 3 engine. The incidents involved a perfectly good # 3 engine breaking its mounts (Fatigue) and then passing over the # 4 engine without knocking it off. This was the result of aerodynamics + and not the result of engine failures.

[alf5071h]

Blue Eagle, GTT, FFF,
It appears that there is some agreement amongst us about the need for two engine out training, but noting the relatively low level of occurrence of such events. However I sense that there is some misplaced over-concern of the difficulty in handling the aircraft.

Ignoring the symmetric two-out scenario, then the asymmetric flight case is still relatively simple. Use the controls appropriately (usually dominated by rudder), maintain the required speed (noting that Vmca2 is likely to be well obove V2), and abide by system or configuration restrictions due to systems loss or degrated performance. There may be a critical period of risk during take off where airspeed is less than Vmca, but this is back to probabilities again.

I indicated earlier and now I strongly suggest that the training for the ‘two out’ scenarios be focused on the circumstances and consequences of the failure and not the flying. In my experience it has been the difficulties surrounding the failures that are far more demanding than the flight handling of the aircraft.

In one example that I am familiar with, an uncontained failure on a four jet (weak design and poor maintenance) resulted in two adjacent engines stopping, leaving a third without indication of N1, TGT, or N2 (T4 blade through cables in fuselage). There was minimum hydraulic power, no flap, no aileron trim (more blade damage), and a ‘small fire in the cabin’ (hot blade in cabin). Also slow pressurization leak, a partial electrical failure, and a fuel leak due a blade though the wing main spar!

The crew was faced with such an array of multiple warnings and alerts that little else other than three engine failures could be deduced; and there was no checklist for that. The Captain elected for a landing back at base (100 nm), but the co-captain (more experienced) suggested an immediate landing at an airfield 50-60 nm away. The crew assessed the flying qualities of the aircraft and the systems that remained operational; they basically built up a picture of the aircraft they were flying. The Cabin crew were politely told ‘not now dear, you fix the fire’. From the flapless, no anti skid, no airbrake, twin engine asymmetric landing everyone walked away from the aircraft, albeit though the grass.

Thus the point I make is not to get too hung up on flight handling with two engines out, but use a training scenario for thinking and planning … a CRM exercise. Also do not over focus on one event, it is most unlikely that there will be a similar one; stick to the basics … airmanship and CRM

[Clear_Prop]

CPB:

Yes I remember seeing that one - was it on 999 or something?

Rotten luck, but great effort by the PF in getting it down.

[GotTheTshirt]

Loma,

Containment is most certainly a certification issue.
Some of it by hardware, some by procedures and some by preventitive maintenance.

The IFSD (In flight shut down) figures are reviewed by both manufaturer and Airworthiness Authorities. Some AD carry the wording ( "to prevent uncontained failure of the engine")

As far as hardware is concerned the turbine and combustion areas are always get the most attention due to higher thermal loads and speeds. There is nothing magic about a nose cowl and al the one I have seen did very little to prevent the blades from making thier own way home.

There is also a burn through certification requirement that in the event of a combustion area rupture for any reason including liberation ( bits comin off) there is a time that the engine must survive. This is done by additional fire proof material in the critical areas.

The 707 reference were just to show that the 2 engines can fail even though the second engine is just sitting there quielty mindind its own business !

The references to prop aircraft is interesting in that there was a problem ( In the good ole days!) called runawy props. It could occur on DC6 and 7, particularly with electric props. For the younger viewers if the coase pitch oil supply to the prop fails the prop goes fully fine and with the aircraft at cruise speed the prop turns very very fast ! Above a certain RPM the CTM overcomes the feathering pump presure and you have a real problem on your hands.
The original procedure was called low and slow technique. You slowed the aircraft to minimum speed and reduced altitude to try and slow the prop down but the grand finale was a gem. All these aircraft had engine oil cocks so you shut of the oil to the engine to sieze the engine and allow the prop shaft to shear and get rid the the offending beast. The procedure did also reccomend that during this "freezing procedure" the aircraft is kept in a turn away from the offending unit to prevent the released propellor from hitching a lift home.

Never saw one on 6 and 7 but we did have a DC3 do it fortunately on take off so the pilot plonked it back on the ground.

[eng123]

In response to the question posed earlier about simultaneous maintenance of engines,it is now standard practice to only carry out maintenance to 'critical' systems,such as disturbing oil or fuel lines,on one engine [for a twin] at a time.Any disturbance,such as gearbox turning cover etc during a borescope insp requires a duplicate inspection.
However,it is acceptable,if needs must,to carry out maintenance to 'critical' systems on both engines at the same time if the individuals reverse their roles ie. who ever does the initial inspection on one engine does the duplicate insp on the other one and vice-versa.

[Cardinal]

Collateral damage after the failure of a single engine is not to be discounted. From a Contintental DC-10 departing Newark, accident report here: http://www.ntsb.gov/ntsb/brief2.asp?ev_id=20001212X20894&ntsbno=NYC00FA122&akey=1

After the uncontained failure of #1 at V1, the following was noted, in addition to high vibration levels on the remaining powerplants:
The number 2 (center) engine exhibited leading edge damage to two fan blades.

The number 3 (right) engine had leading edge damage to all of the fan blades, consisting of tears, rips and material loss. Pieces of fan blade, and material similar to that of the 2nd-stage nozzles from the number 1 engine, were found embedded in the engine inlet acoustic panels.

The front inboard tire of the left main landing gear was ruptured, and the front outboard tire exhibited tread separation, but remained inflated. Impact marks, including punctures and scrapes, were noted on the outboard side of the left engine pylon, the left wing outboard flap, the underside of the fuselage, the left main landing gear access door, the left side of the fuselage aft of the left wing, and a right wing panel outboard of the flap actuator housing.

[nightowl727]

Then there's the Electra over YQT several years ago. Outboard prop abandoned ship, knocking inboard prop overboard as well; one or both ventilated the fuselage. Loss of 2, same side, plus a rapid decompression. :mad:

The gods must have judged the crew as insufficiently challenged, since they also killed a goose on the way down, restricting forward vis. :ugh:

Altho' authorities tend to frown on simultaneous unrelated emergency scenarios in certification and training, might the key word be "unrelated"? - even if some relationships defy imagination :E

- '27 :zzz:

[411A]

T Shirt,
The offending prop mentioned before was on a Mercer Airlines DC-6, the only DC-6 fitted with Curtis-Electric propellers, and the outcome was not a pretty picture.:sad:
Double engine failures (on one side) in four engine types can also be...crew induced.
SV 747SP departing JED (mid-1980's) had an uncontained failure of number two, which thru bits into number one...and the wing etc.
Number one, altho producing full rated thrust, had an engine fire indication, and the Flight Engineer, acting on his own (mouth closed), pulled the number one fire pull handle.
800agl, at max weight, on two engines. A nasty picture.
Knew the Captain involved, and if it was not for his skill, the aeroplane would have been spread all over the beach, by the creek.
Airmanship counts.

PS: The offending F/E had his exit visa and was on the way out two days later. Lucky (for him) he wasn't arrested.

[B2N2]

Once upon a time I experienced 3 engines out as a passenger on a 4-engined piston (DC-6 or DC-7).
Flight from Cusco(Peru) to Lima.(early 80's)
Cusco has an elevation of 9500' and in the afternoon a density altitude of 12000+
Why we even took off is a mystery, we could not get over the tops of the Andes so we flew through the valleys.
After 30 min we lost engine #2(my side ,window).
Spluttered oil and feathered.....
Passengers started praying.......
Little while later #4 sputtered and was feathered.
One hour to go...............:eek:
In the final approach to Lima we flew over "shantytown" at a couple of hundred feet,we could see the squatters look up in amazement.
A few miles out we lost #3..........
Plane hit the runway and took the high speed turn-off before
we were told to evacuate.
We took off running,looking back I saw fuel and oil leaking from the engines and wings.
Quite an adventure for a 12 year old :} :} :}