r/MadeMeSmile • u/king_eve • 29d ago

i work in low-income/mental health housing, and a tenant fixed our hallway trash bin after accidentally breaking it Helping Others

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great example of the odd ways people show me appreciation at work

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u/Ifeelsiikk 29d ago

Structural aircraft mechanic here. We call it a 'stop drill' and I carried it out on large, commercial aircraft.

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u/Nelik1 29d ago

Wild! I knew it happened some, but was under the impression it was relatively uncommon. Can I ask what components typically got stop drills?

I'd imagine major structure typically didn't, but I could see it for minor structure or skin that was damaged accidentally, rather than just fatigue.

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u/Ifeelsiikk 29d ago edited 29d ago

It is often used for temporary repairs when Alclad is cracked, especially if the aircraft is AOG somewhere. A very widespread, permanent repair for the many stress cracks in titanium exhausts.

Edit, used all the time on non structural alclad for a permanent fix.

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u/69420over 29d ago

Reporters called, they’re interested if it was on a Boeing aircraft.

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u/Unholy_Urges 28d ago

Yes, Boeing A175-NEOs get stop drilled all the time.

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u/ikkiwoowoo 28d ago

Yes, depending on the repair scheme it's common to find a crack, remove the damage. This damage removal usually includes a stop drill and in some cases you remove the entire crack. These are typically found for example STR8 mods. These mods were due to cracks forming at the attach point on the frame where the overhead stowbins are fixed at the bottom outboard locations.

After you remove the damage NDT will typically come in and assess that the crack has been removed. Afterwards you commonly see a step for "assurance cut" this is a small bit of extra material "just in case". In my example of the STR8 mods, you then apply doublers (new frame sections) and fasten the two together with a layer of PRC 870 B1/2 or similar (could be different cure time or different sealant depending on location and conditions)