Scribe lines
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Scribe lines
Does the FAA AD on scribe lines on pressurized aircraft fuselage affect only US made aircraft (eg. Boeing) only?
I don't think I've heard of any scribe line inspection or issues on Airbus...
I don't think I've heard of any scribe line inspection or issues on Airbus...
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Scribe Lines
Are you sure it's an FAA AD and not a FAA AC? Nevertheless be very, very careful with scribe lines. Many years ago someone used a scriber to mark the mast of a Westland Whirlwind helicopter and it went undetected until the scribed line propagated into a crack which eventualy lead to in-flight failure and mast separation. If I remember correctly, the accident killed the Commadore of the Queens Flight who was flying that day. I repeat, be very, very careful with scribe lines.
Last edited by Saint Jack; 21st Sep 2012 at 06:17.
not a good idea.
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It relates to all aircraft due to scribing being a basic metallurgical skill. Some manufacturers obviously like to highlight it in AD's because it relates more to their manufacture/ maintenance procedures. Just because a manufacture doesn't raise the issue doesn't mean the engineer shouldn't be vigilant in the consequences and ramifications of scribe lines.
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Wooden boats normally had a scribe line put there by the builder to mark the waterline, as a guide for painting. It would be about .5mm deep, and 1mm across.
Many years ago, someone made a similar one on an aluminium boat.
Salt corrosion and stress (flexing, I guess) did their work remarkably quickly to expand the scribe line into a deep, pitted score along the hull with hairline cracks running off it, and the boat was written off before it sank with all hands and the ship's cat.
Many years ago, someone made a similar one on an aluminium boat.
Salt corrosion and stress (flexing, I guess) did their work remarkably quickly to expand the scribe line into a deep, pitted score along the hull with hairline cracks running off it, and the boat was written off before it sank with all hands and the ship's cat.
For scribe marks read "machine marks" - AD's on BAe146 wings.
Engineers should read these AD's as reminding us that "stress raisers" are apparent in all types and we should be aware of what we see day-to-day - whatever we work on.
Engineers should read these AD's as reminding us that "stress raisers" are apparent in all types and we should be aware of what we see day-to-day - whatever we work on.
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The reason I asked if it only applies to Boeing is because there was a heavy C check done on an ATR I think, where complete paint stripping was done on the fuselage. Inspection after paint stripping the mechanic (who is well versed on Boeing aircraft) reported scribe lines on the fuselage. However, in the ATR SRM there is no such defect as 'scribe line'...
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Yeah, use approved plastic scrappers at all times.. Not some old painting spatula that I've seen in some places! 10810 is a good part number on google.. Skins at the Wing to body fairings on boeings are another favourite place to see nasty man made scratches.. So much aerodynamic sealant to remove..
Cos the ATR SRM doesn't call them scribe lines, bet it will call them scratches!!
Cos the ATR SRM doesn't call them scribe lines, bet it will call them scratches!!
Last edited by Alber Ratman; 24th Sep 2012 at 20:05.
