737 Engine comes of wing in Cape Town
I'm still trying to make sense out of this.
I picked up this link in the other thread running on this site but of course I don't have a login in order to view the referenced pictures
As mentined a few posts above, EI did have a pretty massive fan failure due to birds a few years back and pretty much had only one link left on the front mount plus the cone bolt in the back holding up the engine. So in the case of massive fan damage it's the front mount links that go first. That also might explain the detached inlet cowl.
I seem to recall also that SA had a similar nasty fan failure due to birds on one of their B737-200 about the same time as the EI incident. Of course a few million hours between failures isn't a rash is it
Any pictures of the fan show up yet?
I picked up this link in the other thread running on this site but of course I don't have a login in order to view the referenced pictures
Some excellent close-up photos of the wing, engine mounts and the engine on AvCom ( http://avcom.co.za/phpBB2/viewtopic....=asc&start=180 )
I seem to recall also that SA had a similar nasty fan failure due to birds on one of their B737-200 about the same time as the EI incident. Of course a few million hours between failures isn't a rash is it
Any pictures of the fan show up yet?
nugpot
Many thanks.
Not much collateral damage arround the engine position to support a failure from the fan. Still can't resolve the front vs aft mount chicken vs. egg.
I'll wait and see what turns up tomorrow. If nothing more I suspect that's the last time we'll hear of it.
Many thanks.
Not much collateral damage arround the engine position to support a failure from the fan. Still can't resolve the front vs aft mount chicken vs. egg.
I'll wait and see what turns up tomorrow. If nothing more I suspect that's the last time we'll hear of it.
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I am admiring the flying skills of the pilots, excellent job!
On the other hand this incident strongly confirms the Airbus design philosophy for all the engine mounts. Failure proof principle is strictly applied by using sleeve/bolt design. Each of the two components can take all the design loads with the safety factors.
I don't know how Boeing convinced the FAA at that time to agree that an engine might never fall off and talk them into accepting a simple bolt connection for the 737. I do not know wether this is also true for the 777 and 747.
Frank
On the other hand this incident strongly confirms the Airbus design philosophy for all the engine mounts. Failure proof principle is strictly applied by using sleeve/bolt design. Each of the two components can take all the design loads with the safety factors.
I don't know how Boeing convinced the FAA at that time to agree that an engine might never fall off and talk them into accepting a simple bolt connection for the 737. I do not know wether this is also true for the 777 and 747.
Frank
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"In no other profession are skilled individuals such as pilots required to undergo testing and to demonstrate their proficiency on such a regular basis. Training encompasses a wide variety of subjects and scenarios that hopefully flight crew members will never be called upon to exercise in the operational environment. Yesterday this training paid off – the skills of the crew were called upon and procedures were carried out in a text-book fashion,” says Bricknell."
Pity you don't pay them more, Vern. 737 F/O's on less than $2k a month..tut tut
Pity you don't pay them more, Vern. 737 F/O's on less than $2k a month..tut tut
Paxing All Over The World
fendant I am not an aeronautical engineer but the method of securing the engine of the 737-100 + -200 changed when the -300 arrived with pylon mounted engines and all subsequent models.
There was a change by all designers to place the nacelle ahead of the wing on a pylon, rather than close coupled under it. So I think that comparison of this now obsolete design with that of any later aircraft of any manufacturer is not correct.
There was a change by all designers to place the nacelle ahead of the wing on a pylon, rather than close coupled under it. So I think that comparison of this now obsolete design with that of any later aircraft of any manufacturer is not correct.
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Quoting from nugpot's post of the Nationwide Airlines press statement:
Is this a standard design across Boeing types?
The engine-to-wing supporting structure is designed to release the engine when extreme forces are applied to prevent any structural damage to the wing that may impair the aircraft’s ability to fly.
Are there cases where an engine has detached solely due to an engine failure?
The regulations do not permit a design which intentionally releases a mount under engine induced loading. However s**t happens and when it does, thankfully the aircraft designers are permitted to select a design criteria for the wing which is a tad stronger than the one they use for the engine mount. Meanwhile if an engne does happen to separate for any reason, then a continued airworthiness action under the regs (fix it) is appropriate to bring the design back into compliance (all previous events were addressed by this means).
I finally got to download some much better photos of this event showing the fan and the front mount etc.
Looks like the crap released to the news about ingestion is wrong along with the stuff about mounts being designed to fail etc.
The engine doesn't look like it fell from any significant height and it looks different in my eyes from the previous 3 events. I guess no amount of additional photos off the internet is going to satisfy me until I see a technical report.
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Originally Posted by lomapaseo
Yes Kalita B747, etc. etc.
The regulations do not permit a design which intentionally releases a mount under engine induced loading.
thankfully the aircraft designers are permitted to select a design criteria for the wing which is a tad stronger than the one they use for the engine mount.
Meanwhile if an engne does happen to separate for any reason, then a continued airworthiness action under the regs (fix it) is appropriate to bring the design back into compliance (all previous events were addressed by this means).
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Blue-ice & Engine SEPARATION
Question from NP, two slots above:
"Are there cases where an engine has detached solely due to an engine failure?"
NTSB reported on blue ice incidents in 1991. Tell-tale signature is the long blue-streak from the Fwd Lav.
-- National B727 / 30Apr74 near El Paso, RHS Engine separated at CRZ.
-- AA / 16Apr85 B727 the RHS-engine separated over Las Cruces, N.M.
-- NW / 4Jan90 over Madison, Fla., lost its RIGHT engine due to "blue-ice" from a toilet leak.
Planes landed safety after their engines fell to the ground.
The FAA, after the 1985 incident, required inspection and testing of lines and valves used to empty toilets in 727s and in January 1989 required checks of 737 lavatory systems. A "blue ice" incident occurred 12Feb90 when an Eastern Airlines Boeing 727 was forced to shut down one engine on a flight from Atlanta, Ga., to Sarasota, Fla.
The LHS engine of MD8 aircraft have ingested blue-ice from its FwdLav at CRZ, ??? but engines stay with the DAC-aircraft (??found no separation??).
"Are there cases where an engine has detached solely due to an engine failure?"
NTSB reported on blue ice incidents in 1991. Tell-tale signature is the long blue-streak from the Fwd Lav.
-- National B727 / 30Apr74 near El Paso, RHS Engine separated at CRZ.
-- AA / 16Apr85 B727 the RHS-engine separated over Las Cruces, N.M.
-- NW / 4Jan90 over Madison, Fla., lost its RIGHT engine due to "blue-ice" from a toilet leak.
Planes landed safety after their engines fell to the ground.
The FAA, after the 1985 incident, required inspection and testing of lines and valves used to empty toilets in 727s and in January 1989 required checks of 737 lavatory systems. A "blue ice" incident occurred 12Feb90 when an Eastern Airlines Boeing 727 was forced to shut down one engine on a flight from Atlanta, Ga., to Sarasota, Fla.
The LHS engine of MD8 aircraft have ingested blue-ice from its FwdLav at CRZ, ??? but engines stay with the DAC-aircraft (??found no separation??).
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Originally Posted by iGh
NTSB reported on blue ice incidents in 1991. Tell-tale signature is the long blue-streak from the Fwd Lav.
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Previous INVESTIGATIONS B707, B747, and B737
"... Is it generally agreed that the engines falling off preserved the structural integrity of these airplanes?"
The best summary of the varying design concepts is found in the early 1990's -- some of the reporting may be available on the "web". The _Seattle Times_ had some excellent reviews of the competing design concepts -- Boeing's vs Airbus'.
Engine -Pylon Fuse Pins (break points) WERE relative to earlier Boeing design concepts. Airbus used an alternative concept. Recall the post accident research in the wake of “El Al 1862” B747-200F / 4Oct92 (#3 Eng gyroscopic- separation and then speared #4 Eng). This B747 failure sequence had happened earlier aboard China Air B747F / 29Dec91; same sequence suffered by two B707s on 31Mar92, & 25Apr92.
After the engine separations of the early ‘90’s, there was much study of the two contrasting concepts. Here’s the _Seattle Times_, Jan 9 ’93, pg A9, headline
“AIRBUS AVOIDED USE OF ILL-FATED FUSE PINS / ENGINES DESIGNED TO STAY ATTACHED TO JETS’ WINGS DURING EMERGENCIES”, quote from the story by Achohido:
= = = \/ = = = EXCERPT = = = \/ = = =
“Airbus Industrie … does not use breakaway safety bolts, called fuse pins, to mount jet engines to the wings … Instead, when Airbus engineers began designing jetliners for the first time in the early 1970’s, they ruled out fuse pins in favor of permanently attaching the engines and its supporting structure, called a strut, to the wing.
“’We have no fuse pins,’ said a high-ranking Airbus engineer. ‘In other words, we have designed it so that … will stay attached to the wings in all circumstances.’
“That difference points up a potential hazard posed by fuse pins used on jetliners built by The Boeing Company.
“Designed to snap and release an engine … fuse pins used on more than 930 Boeing 747 jumbo jets … susceptible to corrosion and cracking … used on more than 480 757 twinjets can develop fatigue cracks….
“’… rules require the fuel tanks … and wing to remain intact to avoid the risk of fire,’ said the Airbus engineer. ‘The Boeing and Douglas approach is that, in the event of a survivable belly landing, the engine would come off the wing, hopefully cleanly. Our approach is that the engine would stay on the wing and slide along, again leaving the fuel tanks intact and providing a degree of protection for the fuselage.’
“… FAA spokesman, said the divergent Boeing-Airbus philosophies both meet the existing safety rules….
“… In the late 1970’s, Boeing considered and then ruled out using the Airbus design …”
= = = /\ = = =END excerpt = = = /\ = = =
_Seattle Times_ offered very good illustrated descriptions of the Cone Bolts and Fuse Pin failures (B707, B747, B737 cases): see last week of Dec'92 of the _Seattle Times_, and then during Jan'93 [eg, 9Jan93, pg A9 excerpt above].
_Air Line Pilot_, Aug'93, pg 38: Jan Steenblik did a good story on modifications to the B747 Engine Struts. [similar stories in press of 18Jun'93].
_AW&ST_, 1Nov'93, pg 39-40, "Boeing ... is completing the design of a 747 strut modification that relies on reinforced pylon-to-wing attachment to preclude engine separation in flight. This abandons the clean separation design faulted in Wolleswinkel's [AAIB-Holland] preliminary report...."
Hmmm -- well, after the B737-200 case, maybe the "clean separation design" is still applicable to some Boeing Airliners?
Maybe some hardworking reporter will provide us a review of newer designs of Engine Mounts for B777 and 787.
The best summary of the varying design concepts is found in the early 1990's -- some of the reporting may be available on the "web". The _Seattle Times_ had some excellent reviews of the competing design concepts -- Boeing's vs Airbus'.
Engine -Pylon Fuse Pins (break points) WERE relative to earlier Boeing design concepts. Airbus used an alternative concept. Recall the post accident research in the wake of “El Al 1862” B747-200F / 4Oct92 (#3 Eng gyroscopic- separation and then speared #4 Eng). This B747 failure sequence had happened earlier aboard China Air B747F / 29Dec91; same sequence suffered by two B707s on 31Mar92, & 25Apr92.
After the engine separations of the early ‘90’s, there was much study of the two contrasting concepts. Here’s the _Seattle Times_, Jan 9 ’93, pg A9, headline
“AIRBUS AVOIDED USE OF ILL-FATED FUSE PINS / ENGINES DESIGNED TO STAY ATTACHED TO JETS’ WINGS DURING EMERGENCIES”, quote from the story by Achohido:
= = = \/ = = = EXCERPT = = = \/ = = =
“Airbus Industrie … does not use breakaway safety bolts, called fuse pins, to mount jet engines to the wings … Instead, when Airbus engineers began designing jetliners for the first time in the early 1970’s, they ruled out fuse pins in favor of permanently attaching the engines and its supporting structure, called a strut, to the wing.
“’We have no fuse pins,’ said a high-ranking Airbus engineer. ‘In other words, we have designed it so that … will stay attached to the wings in all circumstances.’
“That difference points up a potential hazard posed by fuse pins used on jetliners built by The Boeing Company.
“Designed to snap and release an engine … fuse pins used on more than 930 Boeing 747 jumbo jets … susceptible to corrosion and cracking … used on more than 480 757 twinjets can develop fatigue cracks….
“’… rules require the fuel tanks … and wing to remain intact to avoid the risk of fire,’ said the Airbus engineer. ‘The Boeing and Douglas approach is that, in the event of a survivable belly landing, the engine would come off the wing, hopefully cleanly. Our approach is that the engine would stay on the wing and slide along, again leaving the fuel tanks intact and providing a degree of protection for the fuselage.’
“… FAA spokesman, said the divergent Boeing-Airbus philosophies both meet the existing safety rules….
“… In the late 1970’s, Boeing considered and then ruled out using the Airbus design …”
= = = /\ = = =END excerpt = = = /\ = = =
_Seattle Times_ offered very good illustrated descriptions of the Cone Bolts and Fuse Pin failures (B707, B747, B737 cases): see last week of Dec'92 of the _Seattle Times_, and then during Jan'93 [eg, 9Jan93, pg A9 excerpt above].
_Air Line Pilot_, Aug'93, pg 38: Jan Steenblik did a good story on modifications to the B747 Engine Struts. [similar stories in press of 18Jun'93].
_AW&ST_, 1Nov'93, pg 39-40, "Boeing ... is completing the design of a 747 strut modification that relies on reinforced pylon-to-wing attachment to preclude engine separation in flight. This abandons the clean separation design faulted in Wolleswinkel's [AAIB-Holland] preliminary report...."
Hmmm -- well, after the B737-200 case, maybe the "clean separation design" is still applicable to some Boeing Airliners?
Maybe some hardworking reporter will provide us a review of newer designs of Engine Mounts for B777 and 787.
[quote] Quote:
Originally Posted by lomapaseo
Yes Kalita B747, etc. etc.
Thank you, I've been reading those threads.
Quote:
The regulations do not permit a design which intentionally releases a mount under engine induced loading.
Only in part 33 which say that specific levels of failure (blade loss test, large bird test) must not result in distress to the engine side of the mounts (of course for other far worse failure conditions you just might get some distress, although quite rare) see again Kalita, blue ice events, etc.
Quote:
thankfully the aircraft designers are permitted to select a design criteria for the wing which is a tad stronger than the one they use for the engine mount.
I believe that it is under wing gust load section etc. requiring that the critical wing structure meet 150% of the worst loads described under the part 33 engine blade loss test. So it's relatively easy to set some minor part like the pylon tmount etc. to break before the wing etc. etc. Lots more could be said but in the interests of brevity I follow the KISS principal
Quote:
Meanwhile if an engne does happen to separate for any reason, then a continued airworthiness action under the regs (fix it) is appropriate to bring the design back into compliance (all previous events were addressed by this means).
Under continued airworthiness any fix can be employed that address the consequences or the cause of a failure condition, either general or specific. If the product does not comply with a specfic regulation under part 33 or part 25 then it's a good idea to at least have a closing action available for that item. In the meantime even restricting the environment it operates within or adding onerous maintainence requirements could be a temporary (for years) solution.
The Kalita event photos seem to show the rear mount was pretty much intact but the engine itself missing. That leaves it doubtful that the mount was overloaded but instead the engine broke away from the mount for other reasons. I believe that the corrective action addressing this did not include the mounts
And finally the suggestion that an interim corrective action for the Nationwide failure should be a grounding of the local fleets based on a loss in confidence of their airworthiness is quite surprising on its surface. the specific failure being discussed is still under investigation and in itself is a benign failure condition to the aircraft and its operation by virtue of both design analysis under the FARs as well as the historical outcomes within a quite extensive millions and millions of hours data bank.
On the other hand if there is strong reason to suspect that a sub population of conditions exist in a very small fleet than the issue is more operator related than design related.
one might suspect that I am still smiting over the localized action of the Danish authorities about the Q400 ) but lets not go there
Originally Posted by lomapaseo
Yes Kalita B747, etc. etc.
Thank you, I've been reading those threads.
Quote:
The regulations do not permit a design which intentionally releases a mount under engine induced loading.
That's what I've been wondering. I've found FAA Part 25 regulations which say that the engine mounts must withstand sudden engine stoppages. Any other place that contains references to this?
Quote:
thankfully the aircraft designers are permitted to select a design criteria for the wing which is a tad stronger than the one they use for the engine mount.
I can't find any specific Part 25 regs concerning this. Any pointers appreciated.
Quote:
Meanwhile if an engne does happen to separate for any reason, then a continued airworthiness action under the regs (fix it) is appropriate to bring the design back into compliance (all previous events were addressed by this means).
And what is the fix supposed to be? Stronger mounts? If so, this suggests that the mounts weren't really serving their intended purpose, but broke away via a "loophole". Do you think it was a good thing that the Kalita engine broke away?
The Kalita event photos seem to show the rear mount was pretty much intact but the engine itself missing. That leaves it doubtful that the mount was overloaded but instead the engine broke away from the mount for other reasons. I believe that the corrective action addressing this did not include the mounts
And finally the suggestion that an interim corrective action for the Nationwide failure should be a grounding of the local fleets based on a loss in confidence of their airworthiness is quite surprising on its surface. the specific failure being discussed is still under investigation and in itself is a benign failure condition to the aircraft and its operation by virtue of both design analysis under the FARs as well as the historical outcomes within a quite extensive millions and millions of hours data bank.
On the other hand if there is strong reason to suspect that a sub population of conditions exist in a very small fleet than the issue is more operator related than design related.
one might suspect that I am still smiting over the localized action of the Danish authorities about the Q400 ) but lets not go there
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And finally the suggestion that an interim corrective action for the Nationwide failure should be a grounding of the local fleets based on a loss in confidence of their airworthiness is quite surprising on its surface.
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