PTO Sheering at the AMAD

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juvat67

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Unread post21 Aug 2017, 21:51

Has anyone heard of AMADs in the aircraft sheering the PTO shafts? So far I have heard of potentially six. Is there a trend going on?
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quicksilver

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Unread post22 Aug 2017, 01:10

What's an AMAD? What's a PTO?
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johnwill

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Unread post22 Aug 2017, 03:03

On F-16, Airframe Mounted Accessory Drive (generators, hydraulic pumps, etc.) driven by a Power Take Off shaft from the engine.
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lowandslow

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Unread post12 Sep 2017, 19:26

Any update on this issue?
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35_aoa

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Unread post13 Sep 2017, 08:31

I'm sure the old guys around here will confirm or correct this, but my understanding is that it was a problem that happened a number of times in the old days of 200/220 motors, and was engineered out of later build 220 and 229 motors. Not sure if there is truth to that, but the old guy who ran our F-16 indoc/training program for a while said he hadn't heard of it happening for many years.
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That_Engine_Guy

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Unread post19 Sep 2017, 03:01

35_aoa wrote:I'm sure the old guys around here will confirm or correct this, but my understanding is that it was a problem that happened a number of times in the old days of 200/220 motors, and was engineered out of later build 220 and 229 motors. Not sure if there is truth to that, but the old guy who ran our F-16 indoc/training program for a while said he hadn't heard of it happening for many years.


Hence the "PTO Shaft Run-out" Check that needed to be performed on the F100 engine PTO mounts.

Earlier PTO mounts on the Engine Gearbox would become 'worn' and could 'wobble' while being driven; the excessive motion would cause the PTO shaft undue stress and it would fracture at it's shear point. (The shaft was designed to break and contain it's self in the event the airframe gearbox seized, it would not seize the engine gearbox, or vise versa)

A duplex bearing was installed in the shaft on the F100 so that the wear would be minimized/eliminated, but the check is still done during JEIM visits to ensure there is no excessive play.

Keep 'em flyin' :thumb:
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[Airplanes are] near perfect, all they lack is the ability to forgive.
— Richard Collins

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