How can mechanic measure distance o

I feel your pain, but more detail required.

I'll assume that if the inspection gave the distance from the edge of the door then you wouldn't be asking the question.

I'll assume that the inspection is giving a fuselage station reference (rather unhelpfully !) We'll do that in our designs ... give a position in the tailcone referenced from the door datum ('cause it is easy for Engineering to do this, but damned near impossible for the guys on the floor to apply it !!?? sigh)

You should be able to determine some fuselage station reference from the SRM. Whether you can do this precisely enough to determine a specific fastener hole is a different question. In lieu of accuracy, estimate a point and inspection a 1/2 dozen holes on either side.

If in doubt, refer to the engineering that created the inspection requirement. "what the eff do you mean ??")

"Hoffen wir mal, dass alles gut geht !"
General Paulus, Nov 1942, outside Stalingrad after the launch of Operation Uranus.

you might be able to sort out dimensions from the centerlines of fastener heads on the outside,
BUT, in general you will need to get access to the inside of the structure.

MIL Acft Tech orders [SRM in particular] usually have fairly detailed series of station/waterline illustrations... so nailing down location is fairly easy... sadly not so for all GA/commercial Acft.

An old trick I have employed... for depot/stress review... is apply clear markings along-the-2-sides and both ends of the visible crack [with chalk or grease pencil]... then annotate the surrounding frames/ribs/intercostals/clips/brackets/stiffeners/longerons/spars/etc that I know-for-sure [and of course... general location like LH forward body, etc]. THEN I've taken a series of photos for context, moving-in-for close-up to the crack/damage [dents/scratches/punctures/scoring/etc]... with noted orientation in each one. Then I send the photos to someone one with access to drawings, to nail-down the exact location... and validate a repair [that I may/may-not have already outlined on the skin].

IF the IPB has detailed views... that another source to start with.

What makes all of this a pain... it existing repairs or un/poorly documented modifications. Grrrrrrrrr


Regards, Wil Taylor
o Trust - But Verify!
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation, Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", HBA forum]
o Only fools and charlatans know everything and understand everything." -Anton Chekhov

Ok it's been 3 decades. But I sure new tech with theoatilite (spelling) but newer tech can measure from a station with in a .001. Are master mylar still been used as well?