Prop falls off Cessna 172

• Feb 3, 2012

• #1

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beaupower32

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Pilot Saves Airplane and Passengers After Propeller Falls Off In Flight


Well, we know one pilot got lucky twice that day.

 

• Feb 3, 2012

• #2

FLYBOYJ

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I saw this the other day. More than likely several of the prop bolts failed. You're supposed to NDI them everytime the prop comes off and they should be replacd at prop overhaul. 172B, hmmmm........

 

• Feb 3, 2012

• Thread starter
• #3

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beaupower32

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Looks like the bolts sheared clean off I would probably replace every time the prop came off. But then again I dont know much about Cessna Maintenance.

 

• Feb 3, 2012

• #4

FLYBOYJ

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The MM calls for NDI only at removal, replacement at overhaul. Those bolts are pretty pricey. There is always a tendency to over torque them, so this would be an end result.

 

• Feb 4, 2012

• Thread starter
• #5

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beaupower32

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Intresting.

 

• Feb 4, 2012

• #6

ccheese

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I would tend to agree with Joe... Over torquing them was probably the problem.

Or.... maybe they were all put on finger tight and not torqued at all !

Only the NTSB knows for sure....

Charles

 

• Feb 4, 2012

• #7

FLYBOYJ

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ccheese said:

I would tend to agree with Joe... Over torquing them was probably the problem.

Or.... maybe they were all put on finger tight and not torqued at all !

Only the NTSB knows for sure....

Charles

Click to expand...

That happened in Mexico - I wonder if their aviation authority was even notified.

Under torque would also cause them to fail. If I remember correctly the bolts go into a backing plate then are safety wired at the hub along the bolt head. I believe another configuration uses self locking nuts.

 

• Feb 4, 2012

• #8

vikingBerserker

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Wow, that was impressive!

 

• Feb 4, 2012

• #9

evangilder

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Someone in the aircraft had an angel on their shoulder.

 

• Feb 5, 2012

• #10

bobbysocks

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bet you it shook like a mother right before that prop flew off!!!

 

• Feb 5, 2012

• #11

GrauGeist

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It'll be interesting to see what the cause was, but I'm going to make a guess here that the bolts were over-torqued and failed.

Had they been loose, there may have been warning signs, such as excessive vibration (and possibly chatter) as well as visible signs of imminent failure (the dust...look for the dust) whereas over-torqued hardware can fail (but not always) internally (where the shoulder meets the threads) and be overlooked during a visual inspection.

Either way, that pilot did a great job keeping his head during the whole ordeal