US and Israeli F-15s Grounded

[haamimhagolan]

I don't know whether anyone has heard this or not, but the worldwide F-15 fleet was recently grounded due to concerns over structural fatigue. It all started with a US ANG F-15C that crashed this past November outside of St Louis Missouri. An investigation concluded that the fuselage had failed just behind the cockpit. The pilot ejected, although he had to be hospitalized from his injuries.

The USAF reports that they have found cracks in the fuselage structure of eight F-15C fighters. All US and foreign F-15A/B/C/D models have been grounded. This includes much of Israel's F-15 fleet, as well as the F-15s serving in Japan and Saudi Arabia. Only the newer F-15E models (including Israel's F-15Is and Saudi Arabia's F-15S models) have been cleared for flight.
http://www.flightglobal.com/articles/2007/11/14/219559/updated-us-air-force-clears-boeing-f-15es-to-fly-after-inspections.html
http://www.flightglobal.com/articles/2007/12/13/220277/usaf-begins-new-crack-checks-as-f-15s-stay-grounded.html

The fuselage cracks are what is typically referred to in the industry as "tired iron". All of the cracks have been found on aircraft that were built back in the 1970s or early 1980s, and appear to be due to normal airframe usage and wear. The USAF and Israel will need to either impliment an ongoing inspection program to ground future aircraft as cracks appear, or they will need to undertake a structural refurbishment program to replace the fatigued parts. Either way, its an unwanted but necessary expense.

[haamimhagolan]

The USAF has approved the inspection process for clearing the worldwide F-15A/B/C/D fleet to flightworthy status:
http://www.af.mil/news/story.asp?id=123081524

In particular, the article notes the following:

90% of all USAF F-15s have been inspected (no values provided for Israeli or other foreign fleets, but they should be similar)
Nine USAF F-15s were identified with cracked longerons
40% of all USAF F-15s have one or more longerons that are not to blueprintThe last point is particularly significant. This has the makings for being a very expensive repair or inspection program.

[haamimhagolan]

The USAF has now issued their formal report on the Missouri ANG F-15 crash:
http://www.acc.af.mil/aibreports/

The web site includes two USAF animations.

The first one depicts a bird's-eye view of the incident. This is the animation that has been picked up by most of the news media.

The second animation, however, is perhaps even more informative: it includes airspeed, attitude and heading information from the flight data recorder, as well as audio from the pilots. Note the g-meter in the lower left-hand corner of the animation. The pilot goes into a hard turn, reaching 6.6-g's at around 41-seconds into the video. It's right after this that the F-15's fuselage breaks up.

The pilot was lucky to get out of this one with no more than superficial injuries. It should be a reminder to us all of just how dangerous this job is.

[haamimhagolan]

More coverage of the maintenance woes that now plague the F-15A/B/C/D fleet:
http://www.flightglobal.com/articles/2008/01/11/220785/special-report-us-air-force-returns-f-15s-to-flight-but-questions-viability-of-fleet.html

The cost of repairing the fatigued longerons is projected at $250,000 each. I suspect that the Heyl haAvir will have no choice but to pay for repairs. The USAF, meanwhile, is contemplating early retirement for additional F-15s, and a possible extended buy of F-22 Raptors.

[haamimhagolan]

The US Air Force has finally approved an inspection plan that would allow those F-15A-Ds with non-conforming longerons - but which haven't yet developed cracks - to return to flight:
http://www.flightglobal.com/articles/2008/02/20/221702/us-air-force-clears-remaining-boeing-f-15s-to-fly.html

The inspection plan calls for close inspection of any non-conforming (below blueprint minimum) longerons every 400 flight hours.

I haven't seen any statistics from Israel or any of the other foreign operators of the F-15A-D, but in USAF inventory some 40% of all aircraft were affected.

The USAF reports that they are preparing a batch of replacement longerons for the nine American F-15s for which cracks were found. However, they have not yet decided whether to install them. The unwritten truth is that the cost of tearing into a complex fuselage assembly like that of the F-15 would far exceed the cost of the longerons themselves. Add to that the possibility that other parts might be damaged in the process, and the likelihood grows that those F-15s that already have cracks will soon become gate guardians.

[howell740]

HAHAHAHAHA!!!!!!!!!!! F-15s suck!!!!!! Sorry I'm a F-16 Crew Chief. Just had to do that. Y'all had topic on it and everything. Besides the F-22 is soooo much more badass.