Cheshire
Topic Author
Posts: 110
Joined: Tue Aug 07, 2001 11:48 pm

F-15 Structural Problems

Sun Dec 30, 2007 10:22 am

F-15s grouded


Air Force inspectors have discovered major structural flaws in eight older-model F-15 fighters, sparking a new round of examinations that could ground all of the older jets into January or beyond, senior Air Force and defense officials said.

The Air Force's 442 F-15A through F-15D planes, the mainstay of the nation's air-to-air combat force for 30 years, have been grounded since November, shortly after one of the airplanes broke into large chunks and crashed in rural Missouri. Since then, Air Force officials have found cracks in the main support beams behind the cockpits of eight other F-15s, and they fear that similar problems could exist in others.


Current and former Air Force officials said that the grounding of the F-15s -- on average 25 years old -- is the longest that U.S. fighter jets have ever been kept out of the air. Even if the jets are cleared for flight, they add, it could take six months to get the pilots and aircraft back to their normal status.

The grounded fighter jets do not include 224 F-15Es, which have been inspected and cleared. The E models, used to support the wars in Iraq and Afghanistan, are about 10 years younger and have a more robust frame.

The F-15A-Ds, meanwhile, are responsible for defending the United States, including flying combat air patrol missions over Washington, a job now filled by F-16s.

"This is going to be a major problem, and it's going to be a difficult one to recover from," said retired Air Force Gen. Dick Hawley, who led the Air Force's Air Combat Command from 1996 to 1999. "You could basically be without the nation's primary air superiority capability for an extended period of time, which puts us at risk."

The disclosure of the cracks comes amid intense Air Force lobbying for the purchase of additional new fighter jets. The Air Force wants to replace its aging F-15s with 200 more F-22 Raptors beyond the 183 already approved by Congress and the Defense Department. Senior Defense Department officials have not agreed that the additional planes are needed or supported their purchase. The F-22s, which cost $132 million each, are manufactured by Lockheed Martin, a Bethesda-based firm.

Significant cracks have been found in the longerons, or structural beams, that support the F-15 fuselage, Air Force officials said -- damage that is believed to be connected to the intense stresses placed on the planes during decades of high-speed maneuvers. The crash last month happened after the back of one plane was ripped off behind the cockpit during a 500-mph dogfight practice. An official crash investigation is scheduled for completion soon.



Some outside analysts have said that the F-15 problems can be fixed and that the extra F-22s are unnecessary. "I don't suspect that the Air Force is lying when it says it has discovered stress fractures in the longerons of the F-15s," said Winslow Wheeler, an expert at the Center for Defense Information and a longtime opponent of purchasing additional F-22s. "But there's no big deal about that. Fix it."

Wheeler said Congress should look into the F-15 issue. In another prominent case, involving refueling tankers, several independent study panels concluded that the Air Force had exaggerated the structural consequences of aging for older planes so that it could make a better case for leasing new ones.

Air Force photos of the damaged beams show clearly visible cracks toward the rear of the fighters' cockpits. Photos and drawings provided to The Washington Post show cracks in similar locations on both sides of the planes and that the F-15 that crashed had undetected damage behind the cockpit.

Maj. Stephen Stilwell, 37, of Missouri was taking that F-15 through basic dogfighting maneuvers Nov. 2 when he started an abrupt turn. At nearly 8 Gs and 500 mph, something went horribly wrong.

"I heard a big rush of air, very loud, like a tornado ripping the roof off a house," Stilwell said. The jet then felt as though it was fishtailing before Stilwell was thrown violently, smashing his left shoulder to pieces. "It was like I was in a car and it's flipping down the road. I felt like the airplane was tumbling and I'm being slammed around, left, right, front and back. . . . It was like I hit a brick wall at 450 miles per hour."

Stilwell's plane had split into two pieces and was hurtling to the ground -- the rear of the craft crashed half a mile from the cockpit and nose. He ejected and parachuted into a wooded area.

"It was the craziest roller coaster I've ever been on," said Stilwell, a commercial pilot with eight years of fighter experience in the Air National Guard.

Similar stress fatigue has been since found in eight airplanes. Four of the damaged aircraft were at the Oregon Air National Guard's 173rd Fighter Wing at Kingsley Field, one of the country's two F-15 training bases. All 25 of the wing's F-15s have been grounded for six weeks.

"The hope is that they will fly again," said Capt. Lucas Ritter, a spokesman for the 173rd. "But we don't have a time frame for when that will be."

Inspectors plan to expand their investigation to include larger areas of the support beams. Senior Air Force officials said that it is unlikely that the entire fleet will be grounded indefinitely but that they are concerned.

"We haven't seen a failure like this before," said a senior Air Force officer, who spoke on the condition of anonymity because the crash investigation is not complete. "I would say it's hard to imagine a more catastrophic event."

Military officials have passed along warnings to foreign countries that have purchased F-15s, including Israel, Japan and South Korea.

Retired Gen. Gregory S. Martin, who led the Air Force Materiel Command from 2003 to 2005, said the F-15 was not designed to last the 30 years it has.

"In my opinion, based on the engineering data we had, we should not be surprised that we're finding some failures in the major structural areas of the airplane," Martin said. "The question wasn't if they would fail, it was when those failures would occur."

Maj. Gen. P. David Gillett Jr., the Air Combat Command's director of logistics, said the Air Force is doing what it can to balance pilot safety with the need to protect the nation. "It's got some problems, but we're going about restoring that capability as quickly as we can," Gillett said.


END ARTICLE

The question I have is this: have any other long term operators of the F-15 such as Japan, Israel or Saudi Arabia experienced the same problem?

And isn't it just typical of the Washington post to insinuate that the problem exists mainly in the right wing?
 
User avatar
kc135topboom
Posts: 11007
Joined: Sun Jan 30, 2005 2:26 am

RE: F-15 Structural Problems

Sun Dec 30, 2007 12:40 pm



Quoting Cheshire (Thread starter):
The question I have is this: have any other long term operators of the F-15 such as Japan, Israel or Saudi Arabia experienced the same problem?

No, those nations have not had the same problem, even though the RSAF, IAF F-15Cs/Ds and JASDF F-15Js are the same age as the USAF F-15Cs/Ds.

Quoting Cheshire (Thread starter):
And isn't it just typical of the Washington post to insinuate that the problem exists mainly in the right wing?

Yes, the Washington Post is a very liberal newspaper. They are not the fair and balanced newspaper the Washington Times is.
 
ebj1248650
Posts: 1517
Joined: Mon Jun 06, 2005 6:17 am

RE: F-15 Structural Problems

Sun Dec 30, 2007 7:00 pm



Quoting KC135TopBoom (Reply 1):
Quoting Cheshire (Thread starter):
The question I have is this: have any other long term operators of the F-15 such as Japan, Israel or Saudi Arabia experienced the same problem?

No, those nations have not had the same problem, even though the RSAF, IAF F-15Cs/Ds and JASDF F-15Js are the same age as the USAF F-15Cs/Ds.

Are they not as hard on their airplanes as the USAF is; i.e. do they not fly their airplanes to its limits as often as our pilots do? Do they maintain theirs better?
Dare to dream; dream big!
 
User avatar
kc135topboom
Posts: 11007
Joined: Sun Jan 30, 2005 2:26 am

RE: F-15 Structural Problems

Mon Dec 31, 2007 2:31 pm



Quoting EBJ1248650 (Reply 2):
Are they not as hard on their airplanes as the USAF is; i.e. do they not fly their airplanes to its limits as often as our pilots do? Do they maintain theirs better?

My guess is the Israelis fly their airplanes just as hard as the USAF does. As far as maintaning the airplanes go, I believe that all the AFs that fly the F-15 maintain it the same way, and to the same degree.
 
N74JW
Posts: 514
Joined: Sat Oct 06, 2007 12:31 am

RE: F-15 Structural Problems

Mon Dec 31, 2007 3:36 pm



Quoting EBJ1248650 (Reply 2):
Do they maintain theirs better?

The Saudis out-source the maintenance of their birds to private contractors. I doubt the Saudi airframes have the hours the USAF/IASF and perhaps JASDF have. S.Korea is not a factor in this discussion as they have not had the aicraft for but two years and the F-15Ks were all new-build airframes.

What to do? Obviously the A/B models need to be replaced, and the C/D models all need a close look. The general was quoted in the article as saying the F-15 was not designed to last thirty years and it did. I don't think the U.S. air defense will be lacking all that much. The continental U.S. does not face too many air threats from our bordering neighbors. If Russian bombers do show-up from the great white North, I think we'll be able muster enough aircraft to meet the threat.

The number of F-22As in service are be allocated to the right spots, Alaska, D.C, and Hawaii. If the F-16s are not fully capable of filling the F-15's shoes, then the USN and the F/A-18E/F might have to step up. Air defense is a task the 'Super Bug' can handle very well and it has two engines for over-water operations. Perhaps an interim purchase of F-16Es by the USAF in an air defense optimization role might be in order. I would love to see the F/A-18E in USAF colors!
rm -r *
 
Blackbird
Posts: 3384
Joined: Wed Oct 06, 1999 10:48 am

RE: F-15 Structural Problems

Tue Jan 01, 2008 1:51 am

I would not be suprized if the IAF better maintains it's planes.


Andrea Kent
 
N74JW
Posts: 514
Joined: Sat Oct 06, 2007 12:31 am

RE: F-15 Structural Problems

Tue Jan 01, 2008 2:54 am

The Israelis do well by their equipment and they should. The IASF has taken all of their equipment into battle at one point or another. No F-15 has been lost to enemy fire in IASF service.

Israel is close to 102:0 when it comes to the F-15. I do not believe that is all skill and luck, but a benefit of superior equipment matched against an unequal adversary.
rm -r *
 
michlis
Posts: 696
Joined: Sat Jul 21, 2007 8:13 am

RE: F-15 Structural Problems

Tue Jan 01, 2008 12:38 pm

I think the point is that the USAF needs to replace its older F-15s. As much as it pains me to say it being the Eagle fan that I am, any repairs made to structural to keep the fleet flying is just a band aid fix. The money would be better spent procuring the additional F-22s and getting them operational.
If you know the enemy and know yourself, you need not fear the outcome of a hundred battles.
 
michlis
Posts: 696
Joined: Sat Jul 21, 2007 8:13 am

RE: F-15 Structural Problems

Wed Jan 09, 2008 5:22 pm

Looks like some F-15s are back to limited flight status. What that means is anyones guess.

http://www.aviationweek.com/aw/gener...Longeron%20Reviews&channel=defense
If you know the enemy and know yourself, you need not fear the outcome of a hundred battles.
 
GDB
Posts: 12653
Joined: Wed May 23, 2001 6:25 pm

RE: F-15 Structural Problems

Wed Jan 09, 2008 8:44 pm

Hell, 25, 30 years, for an aircraft designed for high energy air to air combat, as well as large numbers of the fleet deployed to war at times, (Gulf 1990/1 being the first major US F-15 one), it's done pretty well.

At the other end of the height specturm, look at the Buccaneer, designed for very low level attack, virtually carved from solid as a structure, 15 years into it's service, (11 for the RAF), one had a lethal structural failure at the 1980 Red Flag exercise, where they had for some years been legendary for going low and fast.
Repairs were done, a few were scrapped, but the fleet would have another 14 years of service, including deployment to the first Gulf War, albeit then designating/laser bombing at medium altitude.
 
checksixx
Posts: 1148
Joined: Wed Mar 09, 2005 11:39 pm

RE: F-15 Structural Problems

Thu Jan 10, 2008 2:23 pm



Quoting N74jw (Reply 4):
The number of F-22As in service are be allocated to the right spots, Alaska, D.C, and Hawaii.

What are you trying to say here? And why in the world would we want to put Raptor's in D.C.????
 
User avatar
kc135topboom
Posts: 11007
Joined: Sun Jan 30, 2005 2:26 am

RE: F-15 Structural Problems

Thu Jan 10, 2008 3:03 pm

Now it looks like the USAF will permanently ground some 180-200 of the oldest F-15s. Most of these airplanes will be F-15A/Bs.

USAF Official Says Structural Woes Will Permanently Ground Oldest F-15s



Dozens Of Eagles' Wings To Be Clipped Forever

A possible structural defect in the F-15C Eagle, which led to a November accident -- and, subsequently, the grounding of much of the F-15 fleet -- will likely mean the end of the line for close to 200 of those fighters, anonymous USAF sources told The Los Angeles Times this week.



As ANN reported, the Air Force grounded 452 of its oldest F-15s on November 28, one week after it returned the planes to service following a fleetwide grounding -- including the newest -E model Strike Eagle aircraft -- stemming from the November 2 inflight breakup of a Missouri Air National Guard F-15C.



The Air Force ordered inspections of the aircrafts' four fuselage longerons, which run lengthwise along the body of the plane and hold the aircraft together during high-g maneuvers. Investigators found weakened beams in nine of the aircraft they inspected following the Missouri ANG accident; they still aren't sure whether the beams were defective, or simply deteriorated due to age and stress.



The Air Force will reportedly return 260 of the grounded aircraft to duty soon... but around 180 will likely remain idle forever.



"Many of them may never fly again," one senior Air Force officer told the paper. The results of the Air Force investigation into the problem will be released this week.



Once the Air Force's most sophisticated fighter aircraft, today most of the F-15 fleet is nearly 30 years old. Older models are relegated to duty in Air National Guard units in the United States, while newer F-15Es still fly combat duty in Iraq and Afghanistan.



Air Force officials have cited the F-15s' structural problems as reason for the need for more new F-22 Raptors. The highly-advanced planes are fast, extremely maneuverable, and stealthy... but they're also very expensive. The USAF wants 381 F-22s, to replace its F-15s; the Pentagon has approved the purchase of 183.



"This is grave," a senior Air Force official told the Times. "Two hundred of our air-superiority aircraft are on the ground, and we are acting like it is business as usual."


www.af.mil

www.aero-news.net

How many servicable F-15s are available to be RTS from AMARC?

Is the USAF trying to justify buying more F-22s?

Has the F-15 replacement fighter (F-22) suddenly become the USAF's #1 priority over the KC-X?

The F-15A-D grounding, coupled with the USN premature retiring of the entire F-14A-D force a few years ago, leaves the US in a bad position. I know the F-16A-D force will pick up some of the air superiority missions, but, then that leaves gaps in the CAS missions. The F/A-18A-F cannot back fill all of the F-16 missions.

The ripple effect is going to go a long way for this.
 
Devilfish
Posts: 5261
Joined: Tue Jan 24, 2006 7:52 am

RE: F-15 Structural Problems

Thu Jan 10, 2008 4:38 pm

If that number already includes the F-15s that will be retired in the next round of BRAC come 2009, then it may not be so bad. If not, then the situation is dire indeed.....

http://www.flightglobal.com/articles...-clears-some-f-15s-for-flight.html

Quote:
"The inspections, which are 90% complete, have uncovered nine F-15s with longeron cracks.

'Additionally, approximately 40% of inspected aircraft have at least one longeron that does not meet blueprint specifications,' says ACC. These aircraft have longerons that are thinner in places than specified in the original manufacturing drawings.

ACC says each affected F-15 will have to be analysed to determine if there is sufficient strength in the non-specification longeron to allow the aircraft to return to flight, possibly with subsequent repetitive inspections for cracking.

The command says it has not decided whether it will repair the F-15s with cracked longerons and any of those that cannot be returned to flight after further analysis. A number of F-15s are scheduled to be retired in 2009 under the next round of base closures. 'We need to determine the cost to fix and the return on that cost. That will take another month,' says ACC."




If funding could not be found for Raptors as replacements and with the JSF yet to start series production, is there a realistic chance the USAF would change its mind and order new-build F-15E+ Super Eagles? And would that make sense?
"Everyone is entitled to my opinion." - Garfield
 
bennett123
Posts: 7462
Joined: Sun Aug 15, 2004 12:49 am

RE: F-15 Structural Problems

Sat Jan 12, 2008 12:05 am

GDB

I read somewhere that the problem with the Bucc was that they did fatigue testing on the S1 and simply assumed that fatigue on the S2 would be the same.

Is there any truth in that.
 
buss61
Posts: 37
Joined: Fri Dec 14, 2007 6:27 pm

RE: F-15 Structural Problems

Sat Jan 12, 2008 1:02 am

They should bring back the Tomcat, allow the new Hornets to do the job of the old ones, let the F-16s handle homeland air superiority, and the old F/A-18's to assist the F-16's in homeland security. USMC F-18's will be backup if things really get out of hand. Just my little scenario!!!
Any Time Baby!!!
 
zanl188
Posts: 3447
Joined: Sat Oct 21, 2006 9:05 pm

RE: F-15 Structural Problems

Sat Jan 12, 2008 2:56 am

FYI:

The accident report executive summary, all 4 parts of the full report, HUD video, crash animation, and crack pix are available here:

http://www.acc.af.mil/aibreports/
Legal considerations provided by: Dewey, Cheatum, and Howe
 
CX747
Posts: 5580
Joined: Tue May 18, 1999 2:54 am

RE: F-15 Structural Problems

Sat Jan 12, 2008 3:25 am

30+ years from a piece of hardware that is pushed to the max almost each time it leaves the ground. I think we have gotten our monies worth and more out of the F-15A-D fleet. While the F-15Cs are younger, they are not spring chickens either. These airframes have served us well in the Cold War, Desert Shield, Desert Storm, Operation Northern Watch, Operation Southern Watch, Operation Allied Force, Operation Iraqi Freedom etc. Let's not forget flag pole flying and the deployements to Nellis for Red Flags. At some point we need to look ourselves in the mirror and open up our wallets. 381 F-22s not only take care of our air-superiority short fall but provide us with the capability to dictate the battle field for the next 20-30 years.

One option that was not mentioned was the purchase of another airframe. I know that the USAF was offered a great deal on 100+ F-15Es within the last 2-3 years. Could the USAF potential buy these F-15Es and use them as F-15C replacements? Boeing could make these E models more Air to Air friendly and the USAF could deploy them to the same squadrons now operating the older F-15As etc. If the F-22 is to "expensive", then what can we purchase and afford that will fill the need?
"History does not long entrust the care of freedom to the weak or timid." D. Eisenhower
 
KevinSmith
Posts: 626
Joined: Thu Jan 12, 2006 9:08 am

RE: F-15 Structural Problems

Sat Jan 12, 2008 3:47 am



Quoting CX747 (Reply 16):
One option that was not mentioned was the purchase of another airframe. I know that the USAF was offered a great deal on 100+ F-15Es within the last 2-3 years. Could the USAF potential buy these F-15Es and use them as F-15C replacements? Boeing could make these E models more Air to Air friendly and the USAF could deploy them to the same squadrons now operating the older F-15As etc. If the F-22 is to "expensive", then what can we purchase and afford that will fill the need?

Great idea!!!!! I would love to see that.
No comes the tricky part........funding.
Learning to fly, but I ain't got wings.
 
PlayLoud
Posts: 67
Joined: Thu Jul 19, 2007 7:46 am

RE: F-15 Structural Problems

Sat Jan 12, 2008 5:45 am

Considering the F-15's successor is in production, I think the solution is obvious. Build AT LEAST the 381 Raptors that the USAF says it needs. Building more than the 381 may be necessary given this deal with the F-15. Also, the rate at which they are built needs to be increased.
 
CX747
Posts: 5580
Joined: Tue May 18, 1999 2:54 am

RE: F-15 Structural Problems

Sat Jan 12, 2008 8:40 pm

While I would love to see 381 F-22s, I don't want to see them at the cost of more "Force Shaping" or retirement of other aircraft. That's why I would like to see what our other options are. In lieu of increasing the F-22 buy, WHAT could the US purchase and WHAT could they afford?

F/A-18 E/F?
F-15E?
F-16 E/I?

I do not want to see more fleet retired just to increase the F-22 buy. Thankfully the U-2 was saved but the same can not be said of the F-117.

What I would like to see is common sense dictate future projects but that is unlikely. Instead of investing millions into the EB-52, the USAF should purchase EA-18G "Growlers" and fund joint squadrons with the Navy. It is working with the EA-6B and should continue.
"History does not long entrust the care of freedom to the weak or timid." D. Eisenhower
 
User avatar
Revelation
Posts: 14022
Joined: Wed Feb 09, 2005 9:37 pm

RE: F-15 Structural Problems

Sun Jan 13, 2008 11:31 pm

What's the logic behind finding 9 defective aircraft and retiring 180-200 of them?

Especially since the one that failed in flight was a "C" model, not the "A"s or "B"s being considered for retirement?

I know it costs money to inspect the airframes, but I smell a USAF money grab, and I don't think Congress will let them get away with it.
Inspiration, move me brightly! Light the song with sense and color.
Hold away despair, more than this I will not ask.
Faced with mysteries dark and vast, statements just seem vain at last.
Some rise, some fall, some climb, to get to Terrapin!
 
Devilfish
Posts: 5261
Joined: Tue Jan 24, 2006 7:52 am

RE: F-15 Structural Problems

Mon Jan 14, 2008 6:11 pm



Quoting Revelation (Reply 20):
What's the logic behind finding 9 defective aircraft and retiring 180-200 of them?

Especially since the one that failed in flight was a "C" model, not the "A"s or "B"s being considered for retirement?

This may explain their course of action.....

http://www.flightglobal.com/articles...-cracks-that-downed-usaf-f-15.html

Quote:
"Fatigue cracks started by manufacturing defects in a fuselage longeron caused the in-flight break-up of a Boeing F-15C Eagle on 2 November 2007, the US Air Force accident investigation has concluded.

Longeron cracks have been found in another nine F-15Cs, and manufacturing defects that could potentially cause fatigue cracking have been detected in a further 182 F-15A-Ds. All of these aircraft remain grounded."


I wonder if there's a statute of limitations that would prevent the USAF from initiating claims against Boeing for said defects, given that those were discovered very long after they had accepted, and were just about to retire the fighters?
"Everyone is entitled to my opinion." - Garfield
 
YANQUI67
Posts: 358
Joined: Thu Jan 27, 2005 2:57 pm

RE: F-15 Structural Problems

Wed Jan 16, 2008 12:30 am

Why doesnt the USAF just fix them planes? That is not such a big deal. You shore the plane up, drill the old longerons out and you rivet in a new beefed up longeron, no big deal. All the mech need is a blueprint and a kit with all the parts for the repair. I have seen sheetmetal mechs do a lot harder repairs than this. It just a major sheetmetal repair. I dont get it. It makes me wonder about the Air Forces true intentions. I am sure they could extend the lives of those jets until the new hardware come on line.

Who is online

Users browsing this forum: No registered users and 9 guests