Fan Blades Deformation Limits after Bird Strike
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Fan Blades Deformation Limits after Bird Strike
What are the limits of acceptable deformation (length and depth) of the deformed fan blades of a CFM56 engine? A bird strike warped 4 blades to different levels - and our engineers say they are within limits. Does 6cm long and 0.7cm deep sound ok?
http://imgreview.com/gVMC3
Click on above for picture.
Last edited by BkkPilot; 11th Jan 2016 at 23:28.
Depends what the manual says,which I assume your engineer has quoted in clearing the defect. CFM is quite robust and have seen similar before but don't have manual in front of me,if he/she is happy you should be too!
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5) Local distortion on the leading edge is permitted with these limits: (Figure606)
a) Not more than two locations and the circumferential dimension (Dim.Q) is not more than 0.4 inch (10.0 mm).
b) The depth (Dim.M) into the blade chord is at least six times greater than the circumferential dimension (Dim. Q).
a) Not more than two locations and the circumferential dimension (Dim.Q) is not more than 0.4 inch (10.0 mm).
b) The depth (Dim.M) into the blade chord is at least six times greater than the circumferential dimension (Dim. Q).
If you have to resort to using PPRuNe to verify decisions made by your engineers I have serious doubts about the quality of your operation!!
PPrune is an informal way of cross-checking and learning without directly challenging sensitive ears.
sounds to me like all parties are now satisfied and will sleep well
Absolutely not harsh!!....This is an open public forum and any pilot flying passenger airliners powered by CFM56's should not have to resort to it to verify technical decisions made by engineers
Forget sensitive ears!.....If a pilot queries any decision I make I will happily supply AMM or FIM info for back-up.....If in doubt ask!
Forget sensitive ears!.....If a pilot queries any decision I make I will happily supply AMM or FIM info for back-up.....If in doubt ask!
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boeing_eng, what a pompous high horse you're sitting on?
You know nothing about the guy's situation, yet judging him for asking a question.
Do we want to intimidate or encourage people coming here seeking info to improve their knowledge base before maybe making career limiting moves at their quality operations?
The guy might work at a less than perfect outfit. Believe me, they are out there - maybe not where you are from, but it's a big world out there.
I'd say kudos to questioning and getting ammunition here (or be taught a lesson that he's wrong). That's what this website is for.
You know nothing about the guy's situation, yet judging him for asking a question.
Do we want to intimidate or encourage people coming here seeking info to improve their knowledge base before maybe making career limiting moves at their quality operations?
The guy might work at a less than perfect outfit. Believe me, they are out there - maybe not where you are from, but it's a big world out there.
I'd say kudos to questioning and getting ammunition here (or be taught a lesson that he's wrong). That's what this website is for.
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To play devils advocate I think what a couple of the posters are getting at here is that:
1. The OP obviously had doubts about the certifying engineers sign off WRT these damaged blades.
2. The OP obviously did not seek clarification surrounding these doubts prior to flight of the affected aircraft. (Or the OP would not have been written).
3. The OP sought clarification on a safety of flight issue on an anonymous internet forum. (Nothing wrong with that as has been pointed out above. We all continue to learn).
4. The OP posted that they were now satisfied that the engineers signoff was correct and that there was no safety of flight issue, due to an anonymous answer on this forum which appears technically correct. (I am not doubting the veracity of the answering post containing the detail by the way).
Point 4 is the concerning part of this exercise, and I think this is the thrust of the answers raising the ire of some.
There is no doubt that there are less than perfect outfits out there, but when safety of flight is the issue clarification should be sought from the relevant sources (even these less than perfect operations work to the same technical data as other more seasoned setups). PPruNe possibly should not be included as such.
Rider: I am assuming that this aircraft was operated following the engineers signoff and not deemed AOG pending an adequate answer from the PPruNe engineering community verifying its serviceability.
1. The OP obviously had doubts about the certifying engineers sign off WRT these damaged blades.
2. The OP obviously did not seek clarification surrounding these doubts prior to flight of the affected aircraft. (Or the OP would not have been written).
3. The OP sought clarification on a safety of flight issue on an anonymous internet forum. (Nothing wrong with that as has been pointed out above. We all continue to learn).
4. The OP posted that they were now satisfied that the engineers signoff was correct and that there was no safety of flight issue, due to an anonymous answer on this forum which appears technically correct. (I am not doubting the veracity of the answering post containing the detail by the way).
Point 4 is the concerning part of this exercise, and I think this is the thrust of the answers raising the ire of some.
There is no doubt that there are less than perfect outfits out there, but when safety of flight is the issue clarification should be sought from the relevant sources (even these less than perfect operations work to the same technical data as other more seasoned setups). PPruNe possibly should not be included as such.
Rider: I am assuming that this aircraft was operated following the engineers signoff and not deemed AOG pending an adequate answer from the PPruNe engineering community verifying its serviceability.
There is no doubt that there are less than perfect outfits out there, but when safety of flight is the issue clarification should be sought from the relevant sources (even these less than perfect operations work to the same technical data as other more seasoned setups). PPRuNe possibly should not be included as such.
Exactly my point!
...As far as technical info in this context is concerned, PPRune should not be used as a source of approved data!
Exactly my point!
...As far as technical info in this context is concerned, PPRune should not be used as a source of approved data!
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When an engineer get's all high and mighty like this the best thing is to remind them they are not engineers. They are technicians. The man or woman that designed the system and wrote the troubleshooting of it is the engineer, they just follow someone else's guidelines.
I don't even think your license says engineer on it any longer. The Germans protect the title of engineer from technicians. The man that comes round to fix my broadband is not an engineer. The Sky installer is not an engineer. The man that fixes my fridge is not an engineer and neither is the person who follows the maintenance manual that someone wrote for them.
I don't even think your license says engineer on it any longer. The Germans protect the title of engineer from technicians. The man that comes round to fix my broadband is not an engineer. The Sky installer is not an engineer. The man that fixes my fridge is not an engineer and neither is the person who follows the maintenance manual that someone wrote for them.
