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Old 1st Aug 2014, 12:23
  #10 (permalink)  
Join Date: Nov 2010
Location: CE
Posts: 87
QUOTE: "The only way I know of that a birdstrike can cause an engine fire is if it causes blade(s) separation, which then goes through the casing and severs a fuel or hydraulic line (hydraulic fluid will burn but not very vigourously, it goes like sticky brown treacle). They shoot chickens into the intake at max N1 during development testing to make sure this doesn't happen.
[There was a story years ago that a frozen chicken was accidentally used once, I don't know if that's an urban myth though]"

Your wide of the mark in the whole of your post:
1) The first stage compressor (fan assembly) on a high bypass ratio gas turbine shouldn't penetrate the fan casing otherwise it doesn't get its type approval certificate. Certification tests are carried out during the engine's development stage to ensure this criteria is met. Some engines have high tensile steel casings, others are wrapped with Kevlar.
2) Hydraulic fluid burns extremely vigorously at 3000 PSIG in mist form typical of when a line ruptures. Make that 5000 PSIG on B787 engines.
3)Chickens most certainly aren't used to certify engines ergo the 'urban myth' is exactly that and an utter load of tosh. Birds of a breed consistent with FAA/CAA requirements are raised within a specific time window prior to test and humanely euthanised prior to being weighed and used. This type of testing is a very exact science as there are various requirements to meet. ie. amount of birds in one shot, weight of birds, placement on the fan and combinations of all these.
Of course no amount of testing can account for the extraordinary conditions sometimes met in service, but the engine manufacturers try their damnedest to cover most eventualities.
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