Jeff714 From United States of America, joined Jul 2001, 9 posts, RR: 0 Posted (12 years 3 days 2 hours ago) and read 8101 times:
One of the pics posted today shows an AA 757 at SNA with some damage. How is the damage repaired? By that I mean John Wayne is a little airport and I don't think they have any repair facilities. Are there roving structural mechanics for just such things? I apologize if this question has been asked before.
OPNLguy From , joined Dec 1969, posts, RR:
Reply 1, posted (12 years 3 days 2 hours ago) and read 8034 times:
It depends on where the damage is, and how severe. The aircraft is inspected, and if the damage doesn't exceed certain criteria, it probably can be "maintenance ferried" to a site where the airline has repair facilities. No passengers, or even flight attendants, are allowed on a MX ferry, just the flightcrew. One of the airline's maintenance controllers and a flight dispatcher must authorize the flight, and the paperwork is then sent to the station for the captain.
One of the common flight restrictions for an aircraft with fuselage damage is that the aircraft must remain unpressurized. That usually limits the aircraft to a max altitude of 10,000 feet, and we crank that into the fuel planning for the flight to the repair facility. Other restrictions might involve avoidance of icing conditions, limiting operations to day-only, or cloud-free conditions.
Some types of damage require fixing the aircraft wherever it is. For example, if someone drives a tug into an engine cowling, the cowling will most likely need to be changed on-site, which means a new cowling will get trucked in, and then replaced. If the airline doesn't have its own mechanics at that airport, it'll fly some in to accomplish the repair.
I'll let the maintenance types chime in re: how much damage is too much for a MX ferry, but I've covered the general items...
OPNLguy From , joined Dec 1969, posts, RR:
Reply 4, posted (12 years 2 days 19 hours ago) and read 7922 times:
Also on the subject of Boeing on-site repairs, the most extensive one I've ever heard of was the JAL 747 at ANC sometime back in the 1980s. The 747 has skidded off an icy runway/taxiway and was completely off the runway, and at least 1 or 2 engines had been separated, plus lots of other damage. In the dead of winter, Boeing brought all sorts of personnel, tools, and parts, erected tents, and started the work. It took several months, but IIRC, they essentially rebuilt the 747 from the floorline down. The final bill was about $6 million USD less than the cost of a new 747 then, so I guess the insurance company was happy.
The 747 repair that BrusslesSouth mention is also a good example, and makes me wonder why similar repairs weren't accomplished on the USAirways 767 (N654US) at PHL a couple of years ago. (The aircraft had an uncontained #1 engine failure during an overnight run-up by MX, and the ensuing fire got the wing). Maybe the fire damage, or the schrapnel damage (and there was plenty) was too much, or maybe nobody wanted the future liability for the repair. The aircraft ended up be written off and scrapped on-site.
Srbmod From , joined Dec 1969, posts, RR:
Reply 6, posted (12 years 2 days 13 hours ago) and read 7811 times:
I remember an incident about four years ago @ FL where a tug driver running bags collided with the nose of a DC-9 (the driver ignored the marshaller, and also broke the rule about driving under jetways). It shattered the nose cone, and damaged the front pressure bulkhead, and most of the avionics. The estimated repair cost was like $2 million, and since the plane was being retired in a little more than a month, they decided to ferry it out to the desert earlier than they planned. They fixed it up enough to fly it out to AZ. The pilots followed the 10,000 ft. rule, and got into some bad weather over TX, and came close to crashing the a/c.
B747skipper From , joined Dec 1969, posts, RR:
Reply 7, posted (12 years 2 days 13 hours ago) and read 7798 times:
Dear Jeff -
A type of situation, that you might not be aware of - engine "out" ferries - that is, flying an aircraft (for the purpose of repairing/replacing an engine somewhere else) with a failed engine... only 3 and 4 engine aircraft are legal to be flown with a failed engine, 2 engine airplanes cannot do that...
Like our friend OPNLguy mentioned, in case of maintenance ferry flights, we bring a flight crew qualified to do engine-out ferries, no passengers or flight attendants are permitted on board for that purpose...
This is one great advantage of 3 and 4 engine airplanes versus the "twins", there may be a fairly new 777, one day, making an emergency landing on a small island somewhere, that very well might be scrapped, because it cannot, under any circumstance, be flown out of there...
I have done a few engine-out ferries of 747s in my life, and once, a 707... other than being extremely careful for takeoff contingencies, ferrying with an engine-out does not present too many problems... Here in Argentina, all our 747 crews are engine-out ferry qualified, except captains with limited experience on the that type of aircraft.
M717 From United States of America, joined Dec 2002, 608 posts, RR: 4
Reply 8, posted (12 years 2 days 12 hours ago) and read 7783 times:
"This is one great advantage of 3 and 4 engine airplanes versus the "twins", there may be a fairly new 777, one day, making an emergency landing on a small island somewhere, that very well might be scrapped, because it cannot, under any circumstance, be flown out of there..."
This is a most unlikely scenario, and would occur only in a most dire set of circumstances, where the alternative would have the aircraft "scrapped" already. ETOPS flight and diversion planning don't consider airports where the aircraft "cannot, under any circumstances, be flown out of there".
OPNLguy From , joined Dec 1969, posts, RR:
Reply 9, posted (12 years 2 days 12 hours ago) and read 7767 times:
>>>ETOPS flight and diversion planning don't consider airports where the aircraft "cannot, under any circumstances, be flown out of there".
I think he made his statement solely in the context of not being able to single-engine ferry a twin anywhere...
Either of you two guys recall the Eastern L-1011 that was on a 2-engine ferry from Mexico City-Miami eons ago? They lost a second engine (can't recall if it was just past V1, or after they were airborne and on the climbout) and they came back to land on a single engine. Hot day too, IIRC. Must have been something to see...
FDXmech From United States of America, joined Mar 2000, 3251 posts, RR: 32
Reply 10, posted (12 years 2 days 11 hours ago) and read 7751 times:
My hats off to the sheetmetal/structural mechanics. These guys are truly the miracle workers of the airlines. These guys definitely don't get the credit or recognition they deserve. The systems guys fix the systems, but the structures guy fix the airplane. A little kid watching my dad fix the car might describe the awe I feel for these artisans. They work from the airplane, structural repair manual, which when I look through it, might be similer to a layman reading a complex system schematic or wiring diagram, it's over my head, but oh so interesting.
B747Skipper From , joined Dec 1969, posts, RR:
Reply 12, posted (12 years 2 days 10 hours ago) and read 7727 times:
Oh OPNLguy - I am an old fart - I am sure our friend M717 did not mean it the bad way - I am quite sociable... and always smiling...
The problem is, in being old fashion as I am, I only want to fly airplanes (i.e. 747) with 3 cockpit flight crews (no flight engineer does not exist for me) and with 3 or 4 engines, I swim well but cannot do it from the middle of the ocean to the nearest shores... ETOPS still is engines "turning" or... pilots swimming - at least with my philosophy from the last century... and don't you tell me I was flying with the Wright Bros. and gave pilot training to von Richtoffen...
I know we have a lot of A-330, 767 or 777 admirers here, so I shall stay quiet with my 4-engined Boeingosaurus...
Happy contrails -
Check out the "substantial damage" to the fuselage of this Delta Airlines MD-88. The accident occured when the tug "jackknifed" and hit the jet during pushback at the Denver Intl Airport on April 22, 2003. Poor airplane!
Prebennorholm From Denmark, joined Mar 2000, 6716 posts, RR: 54
Reply 16, posted (12 years 2 days 9 hours ago) and read 7661 times:
Many years ago a 733 ran off the runway at Roenne Airport on the island Bornholm in the Baltic Sea. If I remember well the gear collapsed, and both fuselage and one wing and one engine were severely damaged.
Boeing technicians worked on the site probably for a couple of months, and then the plane was as good as new.
Always keep your number of landings equal to your number of take-offs
Dalmd88 From United States of America, joined Jul 2000, 2692 posts, RR: 14
Reply 18, posted (12 years 2 days 5 hours ago) and read 7596 times:
That 757 damage wasn't very bad. I quick guess is the replaced the slat, replaced the fillet fairing with maybe a repair to the fairing support. It doesn't look like they got into the belly of the plane. As for our poor Delta MD-88 yes that took some time and some guys from Base mint in ATL made a lot of OT on that job. I was at work the night it happened. The engineers were down in our overhaul bay looking at our plane to see what was involved. Meanwhile a eighteen wheeler flatbed was loading up with jacks, shoring and the hydraulic mule to swing the gear. We all went into the office to see the pictures. The one posted here isn't the best view, but it's the only one someone outside of the company took.
That job was a good bit of work I bet. What is the most fun part of doing it? Cutting into the side of the plane is cool. After you clean the hole up you just stand back and say what a mother of a hole that is. The real trick is a good layout. The Structural Repair Manual(SRM) is very general for most repairs, that maybe why some guys are overwhelmed by it. It usually says make the doubler(the patch) out of one gauge thicker metal and will call out for three rows of fasteners around the edge. It will tell you what type of fastener, typically rivets and hilocks. The SRM is general so you tailor the repair to your damage. If your smart you lay out the cut to make the fasteners fall in easy to reach places. It isn't always possible, but you try when you can. The other caveat is to do no more harm. I've seen many jobs grow to larger repair due to a sloppy drill or ziz wheel.
Repairs like the one on the MD-88 above aren't really hard. The just take some planning and patience.
737doctor From United States of America, joined Mar 2001, 1332 posts, RR: 37
Reply 21, posted (12 years 2 days 2 hours ago) and read 7547 times:
Speaking of three-engine ferries, here is link to an incident of which I was intimately aware. I know the mechanic that signed off the MX release. He was watching while the aircraft made its takeoff roll and was horrified as the plane crashed. It affected him very deeply. I was working in SLC at the time and met the FO's widow. He was from Utah and fairly new with the company; after her husband's death, she came out to see one of our other airplanes to get a better sense of what her husband did for a living. I'll never forget the look in her eyes.
N949WP From Hong Kong, joined Feb 2000, 1437 posts, RR: 1
Reply 23, posted (12 years 2 days ago) and read 7516 times:
On October 18, 1983, a Lufthansa Cargo 742F (D-ABYU) aborted a takeoff (probably at speeds above V1) on runway 13 at Kai Tak. Whether by accident or on purpose, it veered off the runway onto soft ground right at the end of the runway (possibly avoiding a splashdown into the harbour). The nose gear and the wing-mounted main gears collapsed, punching huge holes into the lower fuselage and through to the main cargo deck. All four engines and pylons were also torn from the wings. I remembered it spending almost a year in HKG being rebuilt. Had it not been such a young aircraft at the time (only 2-years old), it would almost certainly have been scrapped.