Mrs. Gap and I were returning from NYC yesterday on Deltas flight 459, a Boeing 767 with tail number 188 and we noticed something I’ve never seen before. The sun was very intense on the port side of the aircraft and on the cabin panels below and forward of the windows there were vertical steaks of light showing through those panels. It was clear (shown by waving a hand in front of these streaks) that they were caused by illumination coming from outside, not inside. We summoned the flight attendants, and neither one of them had seen anything like that before. They took photos with their company phones.
What in the wide wide world of sports would cause that? Our first thought was cracks in the skin of the plane and in fact we joked about it with the FA’s. (Gallows humor?) My next guess was refraction of light though slight harmless gaps in internal panels near the windows. Anyone here (LSLGuy?) know what might cause that kind of thing?
I’ll let LSLGuy answer, since the planes I’ve flown are anything but airtight. But consider: 767s are pressurised. If there were cracks or gaps in the skin and interior, it would not have held pressure.
ETA: Pay no mind to the gap! 
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Yeah, I knew I was gonna get called out on the user name/post combo.
I agree Johnny, I didn’t really think it was skin cracks, but being a sick and twisted individual I couldn’t help the Hawaiian Air reference I mentioned. Still, it was a wee bit disconcerting that neither of the two flight attendants had seen this effect before.
The interior panels are decorative, made of separate pieces clipped onto the actual structure and covering insulation blankets and wiring and such. There’s room for internal reflection of light from the windows off of the insulation etc. and reaching the gaps between the panels. Something may not have fit as tightly as it should, but it wouldn’t have been anything functional. If there had been an actual air leak, you’d have heard or felt it.
Were they still loading the luggage? Was the cargo door still open? Could be that the cargo bay was flooded with sunlight, which was then reflected up through the inside panels. Just a guess.
mc
mikecurtis, the plane was at 36,000 ft. when we noticed the effect. Cargo doors of course, were long since closed. ElvisL1ves, as you point out, we also thought it may just have been light reflected off of panels, etc.
I don’t suppose I’ll ever know for sure, but having never seen anything like that in all my previous flights and it was unusual enough to cause the FA’s to photo it since they were surprised by it also. F’in weird though.
It was tiny gremlins behind the panels, cutting the chassis with a tiny acetylene torch
It’s light reflecting through the window trim and off the insulation blankets. The outer blanket fabric is shiny silver material. That plane was built back in the 80’s and things have settled over the years. I can find the exact date the plane tomorrow at work.
Honestly, at 36,000 feet, the plane has no gaps in the skin. You’d have died if it did.
Optical illusion?
I think we got a winner here, racer72. www.airfleets.net has this planes history, it’s first flight was March 10, '96. That’s more than enough time for the insulating blankets to have shifted about and cause what we saw. I love this fucking place! Thanks for the clue, and to all who gave their two cents.
There would have been a draft if there were gaps in the skin.
Melbourne, thanks to you I’ve had a good laugh, whether or not you meant your response to be humorous. Describing the result of a gap in the skin of a plane traveling at 498mph. at 36k feet as “a draft” is like a Brit saying WWII was “a spot of bother with that Hitler chap”. Perhaps a soothing way of saying explosive decompression. :eek:
Well just thank you for that link. That’ll kill a few hours a week.:mad:
Seriously, I added it immediately. 
The US Armed Forces went to an all volunteer military in 1973.
The SR-71 is a leaky aircraft until heat from air friction expands the metal.
According to Boeing firing orders, 767 line number 188 was delivered to Delta back in November of 1986. I haven’t had time to search the link though.
Just had time to do a little more checking, that plane was actually line number 631 at Boeing, delivered to Delta on October 17, 1996. The tail number listed by the OP is something totally different. 767 line number 188 was delivered in 1986 to Delta but was scrapped back in 2013. In my almost 33 years at Boeing, the 767 and 787 are the only planes I haven’t worked on.
The actual question’s already been answered, so I’ll go on about this back-and-forth:
Depends.
The hole in the back of the airplane that cabin air flows out of is the size of a cafeteria tray when fully open. Fully closed it’s still several square inches across.
For darn sure any tear in the skin runs the risk of growing until a couple square feet of skin are missing and a rapid decompression ensues. The fuselage structure is designed with that in mind so any tear only grows so far before it’s stopped. At that point we hurry down then go land someplace and you get to wear the silly mask for few minutes. Not a zero-risk event, but not really a big deal either. Loss of pressurization events occur about once a month in the US industry, with rapid events occurring about once a year. It generally doesn’t make the news because it’s not really newsworthy.
In the Aloha accident Aloha Airlines Flight 243 - Wikipedia the whole top of the airplane was a corroded mess and the rip-stop structure ripped right along with the skin. Eventually it tore far enough that the edge of the tear got to less corroded = more intact structure. Where the progressive failure promptly was stopped as designed. The loss of that much structure left them in a very precarious spot; the airplane could have broken in two pretty easily.
OTOH:
If someone carefully cut a gap of a few square inches in the skin and reinforced it properly so it wouldn’t tear further the airplane would pressurize just fine. The noise from the opening to the outside world would be horrendous. As would the breeze from outflowing cabin air near the hole. But it’d be nil risk.
In fact, a lot of people’s service ended because of gaps in their skin…
Maybe it was a stealth version of the 767. When it went into stealth mode, the light could shine through.