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lynn789
2nd Mar 2011, 22:52
for a long time the general wisdom was that the shear pins were partly there so the engines would break off on hitting the water to stop the engines digging in and destroying the plane

now it seems from the hudson river ditching that the jet has to touchdown tail first to keep the engines above the water as long as possible, and the shear pins most likely wont allow the engines to break off during ditching
howcome everyone seemed to have it wrong for so long?

is it now accepted that the shear pins are there only so a badly vibrating engine can fall from the wing

john_tullamarine
2nd Mar 2011, 23:02
the general wisdom was that

perhaps in some circles but I suspect not amongst operational folk

the hudson river ditching

I suspect that the good folk flying the aircraft at the time were more intently concentrating on impacting the water at their understanding of the appropriate body angle and speed without thrust. They would have been mindful of the drag implications of the underslung engines but that would have been a secondary consideration ... best managed by attending to the first.

Machdiamond
2nd Mar 2011, 23:06
The shear pins are there so that if the engine needs to go (bad landing, vibrations, ditching or whatever), it does not take the wing with it or open up the fuel tank. If it doesn't need to go, it won't.

lomapaseo
3rd Mar 2011, 01:07
howcome everyone seemed to have it wrong for so long?



blame it on the press to simplify it for the public.:E

Aviation insiders know better.

The idea is to protect the wing box and fuel tanks from any survivable load comming in from the pylon whether engine induced, manuever induced or just a bad ditching.

History seems to have verified this concept no matter what you call it.

bubbers44
3rd Mar 2011, 01:33
I really don't think ditching has anything to do with the shear pins on the engine pods. They keep an engine seizure from causing the wing to fail. Engineers don't design airplanes to ditch. They design them to fly safely.

barit1
3rd Mar 2011, 03:35
The Hudson ditching was on extraordinarily smooth water, which undoubtedly accounts for 50% of the engines remaining attached.

GarageYears
3rd Mar 2011, 13:59
:E Should we campaign for "engine release pins"..... I vote that switch at least has a guarded cover.

(I believe from Sully's perspective one of his biggest concerns was digging an engine in asymmetrically and cartwheeling.)

- GY :ooh: