Why we tie down Aircraft

[B47]

Originally Posted by SKnight

True, very true.

And of course for those who know aviation maintenance, having someone who's qualified and willing to sign off the FAA Form 337's.

[rockfordroo]

"FOD walk"? - sounds military to me.

FOD = Foreign Object Damage. In the Navy we did a "FOD walk down" of the ramp (the area where the planes are parked) every day looking for FOD, i.e., any crap that shouldn't be there that could get sucked into an engine. FOD is mostly a jet engine concern. Reciprocating engines don't pick up FOD like a jet.

When they taught us about FOD, they showed us a video of a jet engine on a test stand. They dropped a 1/4" nut into it at 100% power. It blew itself apart in many pieces. Easy to see how a goose can kill an engine (as in Capt Sully on the Hudson River a few years ago).

[B47]

Originally Posted by rockfordroo

FOD = Foreign Object Damage. In the Navy we did a "FOD walk down" of the ramp (the area where the planes are parked) every day looking for FOD, i.e., any crap that shouldn't be there that could get sucked into an engine. FOD is mostly a jet engine concern. Reciprocating engines don't pick up FOD like a jet.

When they taught us about FOD, they showed us a video of a jet engine on a test stand. They dropped a 1/4" nut into it at 100% power. It blew itself apart in many pieces. Easy to see how a goose can kill an engine (as in Capt Sully on the Hudson River a few years ago).

Oh yeah - very familiar with FOD,FOD walks on the flight line,etc. While mostly connected with jet engines,FOD is also dangerous to aircraft tires ( similar to road hazards for car and truck tires).

[SKnight]

Originally Posted by B47

Oh yeah - very familiar with FOD,FOD walks on the flight line,etc. While mostly connected with jet engines,FOD is also dangerous to aircraft tires ( similar to road hazards for car and truck tires).

Best FOD caused non direct engine damage I can think of is the Concorde crash. Debris on the runway blew a tire out which opened the fuel tank and damaged the engine.

[B47]

Originally Posted by SKnight

Best FOD caused non direct engine damage I can think of is the Concorde crash. Debris on the runway blew a tire out which opened the fuel tank and damaged the engine.

Not everyone is buying into that scenario although it's the most common probable cause.

The British (don't remember if the government or the airline) were trying to hold Continental Airlines responsible for the debris as they claim it came off their DC-10 which had taken off on the same runway as the Concorde just prior.

[SKnight]

Yeah, to include them going after the mechanic that last touched the metal. It's a mess, part of why I didn't get into aircraft maintenance.

[B47]

Originally Posted by SKnight

Yeah, to include them going after the mechanic that last touched the metal. It's a mess, part of why I didn't get into aircraft maintenance.

I was still working when that accident occurred. I never heard anything from the Houston FAA office that held the Contineatial Airlines certificate. And I never heard that the FAA inspected the Contineatial DC-10 that the debris allegory came off of. I always thought that was a little strange.

[rattleNsmoke]

When working at Avco Lycoming years ago, I was on a tour of the test engine facility where engineers would toss frozen chickens into the impellers to see how much they could take without exploding. Cool job I thought......

[Arefbee]

Why frozen chickens??? A rock would be cheaper and less to clean up!

The school I went to had an Messerschmidt ME-262 engine and actually would run it up sometimes - until someone dropped a nut into it. It is now a cut-away display of that engine.

That looked like an all composite aircraft. I'm guessing the avionics were salvageable, maybe the tires, possibly the seats. Not much else. FOD would be all that was left.

[rattleNsmoke]

Ehhh...My guess is that the employees were in the mood for chicken salad that day.

[B47]

You guys are missing the point on this bird/rock ingestion and jet engines. It's not funny,but it is serious.

If you Goggle 14 CFR 33.76 and open "Bird Ingestion" you will read about the FAA requirements that a jet engine manufacturer must comply with before his engine can be FAA certificated for use on aircraft.

The regulation requirements clearly calls for a "bird" (the size of the bird varies according to many factors,including the engine inlet size) to be shot into the engine to see if the engine can survive the bird ingestion and keep turning and burning while operating.

So No these guys just didn't want chicken salad sandwiches - they are just complying with the regulations to keep the flying public safe. This is just one of the zillion FAA requirements aircraft and engine manufacturers must show compliance with before their product can be FAA certified. It's one reason aircraft are so expensive and yet so safe.

Feel free to PM me if you wish to.

[B47]

Originally Posted by Arefbee

Why frozen chickens??? A rock would be cheaper and less to clean up!

The school I went to had an Messerschmidt ME-262 engine and actually would run it up sometimes - until someone dropped a nut into it. It is now a cut-away display of that engine.

That looked like an all composite aircraft. I'm guessing the avionics were salvageable, maybe the tires, possibly the seats. Not much else. FOD would be all that was left.

They use birds because it's highly unlikely that a jet engine is going to ingest a rock while flying.

[Ford Idaho]

nasa

thaw the chicken.

[B47]

Originally Posted by Ford Idaho

nasa

The reg doesn't specify that the bird used must be frozen,but they all have been frozen in my experience.

The tests I have seen use some sort of air powered cannon to shot the bird into the operating engine. This might be on YouTube.

[rattleNsmoke]

I knew exactly why they used chickens. I was making light of the practice because we all got a good laugh at Lycomings expense. Bird strikes are all too common and many we'll never hear about unless there is an engine out, airframe damage or work in the industry and read the reports.

[Ford Idaho]

Originally Posted by B47

The reg doesn't specify that the bird used must be frozen,but they all have been frozen in my experience.

The tests I have seen use some sort of air powered cannon to shot the bird into the operating engine. This might be on YouTube.

Myth busters built an air powered "canon" and pasted some chickens
(thawed)on air plane windshields.

After blasting two or three they found out the windshields were not rated to handle "bird strikes" LMO for couple of minutes...

[B47]

Originally Posted by Ford Idaho

Myth busters built an air powered "canon" and pasted some chickens
(thawed)on air plane windshields.

After blasting two or three they found out the windshields were not rated to handle "bird strikes" LMO for couple of minutes...

I forgot about windshields and bird strikes. 14 CFR 25.631 does require a bird strike against aircraft windshields test before certification and calls for a 8 pound bird.

14 CFR 25 is the large aircraft certification requirements.

[rockfordroo]

calls for a 8 pound bird

"What's a henway?"

"About 3 lbs"

(Sorry, couldn't help myself.)

Seriously, I don't think chickens get that big, do they? (I'm no farmer). If not, I wonder what they're using. Small turkeys?

[B47]

Originally Posted by rockfordroo

"What's a henway?"

"About 3 lbs"

(Sorry, couldn't help myself.)

Seriously, I don't think chickens get that big, do they? (I'm no farmer). If not, I wonder what they're using. Small turkeys?

If you read my previous posts on this thread and read the FAA regs I quoted
( and I don't expert many of you to do so as many find them dry,but I find them interesting) you will see that the regs (14 CFR 33.76) don't call for a particular type of bird, they simply say "bird". None of the bird strike regs contain the word "chicken". Also the engine ingestion reg bases the bird size on the size of the engine inlet.

The windshield reg (14 CFR 25.631) does require a 8 pound "bird".

[jevanb]

not aircraft have tiedowns, our line crew forgot to chock all the tires and hook up the nose gear scissors, wind storm crept up at night and this is what I came into work to find. took it out of service for 2 months while boeing got us a repair scheme