F-15E crashes in Mideast, crew ejects safely

[Toro]

US F-15 crashes in Mideast, crew ejects safely

Not many details, but good to hear the crew got out safe.

[Cap-10]

WTF is going on?

We lost Pitbull/Lag back in 2009....Meso/Mask punched out in 2011....feels like we just got done burying Piston and now this.

Words can't begin to describe how happy I am that the crew made it out!!!

Cheers,

Cap-10

[brabus]

Seriously, been a rough few years for the beagle bros. Glad the dudes made it out!

[BQZip01]

Just saw this on Yahoo! Glad they got out ok. What's going on?

[HeyWatchThis]

Just saw this on Yahoo! Glad they got out ok. What's going on?

I think we all know the answer to that....they obviously didn't have their reflective belts on from dusk-dawn

But in all seriousness that they are safe!!

[HuggyU2]

I feel for you -E model guys.

The AF is completely mis-utilizing that aircraft, and running the fleet into early retirement needlessly.

Can I assume y'all are seeing a lot more age-of-the-fleet writeups on your jets?

[Hacker]

It's been a few years since I've been in one, but in my last exposure to the fleet it was not, shall we say, aging gracefully.

[Ram]

It's been a few years since I've been in one, but in my last exposure to the fleet it was not, shall we say, aging gracefully.

I feel for you -E model guys.

The AF is completely mis-utilizing that aircraft, and running the fleet into early retirement needlessly.

Can I assume y'all are seeing a lot more age-of-the-fleet writeups on your jets?

Both can be said about the Viper, as well. Lots and lots of hours on the jets in the last 10 years...

[Cap-10]

I feel for you -E model guys.

The AF is completely mis-utilizing that aircraft, and running the fleet into early retirement needlessly.

Can I assume y'all are seeing a lot more age-of-the-fleet writeups on your jets?

The F-15E has been constantly deployed since late 1990 for Desert Shield and it shows....one of the 335th "Chiefs" jets that just got back from Bagram went over 10,000 hours during the deployment...the FTU jets (first F-15E's off the line) are in the high 6, mid 7,000 range. IIRC, the original design limit was 4,000 hours and I know it had been extended to 8,000...not sure what the current approved hour limit is.

Definitely looks like more jets are having hydraulic issues, generator issues, etc...hell, I don't think we have a single jet on base that has a Left Vertical Stab light that works.

In my last year, I've personally had more minor flight control issues (CAS first fail or Lat stick limit type of things) and seen more gear fail to retract or door sequencing issues than in my first 9yrs in the airplane.

Not sure now much longer the jets can take it!

Cheers,

Cap-10

[Steve Davies]

The F-15E has been constantly deployed since late 1990 for Desert Shield and it shows....one of the 335th "Chiefs" jets that just got back from Bagram went over 10,000 hours during the deployment...the FTU jets (first F-15E's off the line) are in the high 6, mid 7,000 range. IIRC, the original design limit was 4,000 hours and I know it had been extended to 8,000...not sure what the current approved hour limit is.

The designed fatigue life for the F-15E is 16,000 hours.

[guineapigfury]

The designed fatigue life for the F-15E is 16,000 hours.

So that's about 10 more years at this rate of usage? The JSF might be ready by then ... but probably not.

[Crosswind]

I'm pretty sure the design life was originally 8,000 hrs, but a study was conducted saying "yeah they should be though enough for double that as long as we monitor these things".

In any case, what possible level of engineering could project 16,000 hrs of wear and tear on an airframe with a 90% confidence? Especially while we cut maintenance and back shop.

[Steve Davies]

I'm pretty sure the design life was originally 8,000 hrs, but a study was conducted saying "yeah they should be though enough for double that as long as we monitor these things".

In any case, what possible level of engineering could project 16,000 hrs of wear and tear on an airframe with a 90% confidence? Especially while we cut maintenance and back shop.

No, the Strike Eagle was always intended to have a 16,000-hour fatigue life, even before it had won the DRF competition.

I think that the study you refer to occurred prior to the competition, when McAir already knew that the NACA 64A aerofoil section used in the Eagle was good for 8,000 hours and used almost two decade's worth of fatigue data from the F-15A to predict that it was good for double that. They therefore left it untouched.

The F-15E fuselage, however, was specifically designed to meet the 16k requirement. Again, they had the fatigue data from almost 20 years' worth of Eagle operational flying, so they knew what they needed to change and what they could leave untouched in order to satisfy the 16k milestone. In the end, the focused on the rear fuselage keel, and developed new manufacturing techniques for titanium - "Superplastic Formed (SPF) Diffusion Bonding (DB)", otherwise known as "BLATS" (built-up, low-cost advanced titanium structure). They also thickened the bulkheads compared to the Eagle.

[Crosswind]

Steve, great stuff. That kind of research is probably why I'm enjoying Red Eagles so much right now.

A few questions (not scoffs) - If the F-15A/B was introduced in 1976, and the E model in design finalized in the mid 80s, where did they get 20 years of data?

I would also add that the loads on the strike are borderline mutually exclusive from that of the C model. That, and in the early 80s the simulation software that could project that kind of fatigue just wasn't that robust.

In any case, good info. But more importantly, glad to hear these guys got out. .

[Jaded]

They can put aircraft on a "paint shaker" and simulate years of flying fatigue in much less time (i.e., if they shake it for a week, that's 168 hours of flying fatigue, which is obviously a lot more hours than you are going to operationally put on an airframe in a week). They're doing that with F-16s right now to determine what needs to be replaced for the SLEP to extend the Viper's life.

[Hacker]

I would also add that the loads on the strike are borderline mutually exclusive from that of the C model.

How so? The most load-sensitive parts of the airplane are the engine mounts and the tail booms.

[busdriver]

High flight time on airframes is hardly limited to one or two MDS. They have all gotten the shit beat out of them the past 10 years.

[Steve Davies]

Steve, great stuff. That kind of research is probably why I'm enjoying Red Eagles so much right now.

A few questions (not scoffs) - If the F-15A/B was introduced in 1976, and the E model in design finalized in the mid 80s, where did they get 20 years of data?

I would also add that the loads on the strike are borderline mutually exclusive from that of the C model. That, and in the early 80s the simulation software that could project that kind of fatigue just wasn't that robust.

Crosswind

Thanks for the compliments on the book. Glad that you're enjoying it (so far!).

My reference to 20 years was, as you point out, incorrect. From memory, I had 1972 in my head for Eagle IOC, whereas this was of course the year of the first flight. My bad. Let's just say then, they had fatigue data stretching back to 1972 - probably enough for them to work with.

I'm no engineer, so I can't answer your specific questions about the robustness of their simulations, but they did use an Iron Bird simulator for extended lifecycle testing of the flight controls and hydraulic systems. It maybe that their Iron Bird also had a hydraulic load testing function. I don't know.

Ref. comparison with the loads experienced by the Eagle fleet, McAir factored in a much more demanding set of criteria - namely that the Strike Eagle would spend much, much more time in the denser, more turbulent air of the low-level environment. I don't have the data for what percentage of time it would spend there, but given that it was to replace the F-111F and was designed specifically for the Fulda Gap scenario, I'd hazard a guess at "the majority" of time.

Again, not an Engineer, so cannot comment on which variables that had an impact on, but they certainly weren't planning for the E-model to be spending time at medium-altitude delivering PGMs from relatively sedate delivery profiles. Since that's exactly what the Strike Eagle has been doing since Desert Storm (with some noteable exceptions), I'd take a wild guess that even if McAir's original engineering calculations were out by 10 per cent, the actual *structural* fatigue life of the Strike Eagle fleet is probably better at this point in time than originally forecast.

[Dupe]

In my last year, I've personally had more minor flight control issues (CAS first fail or Lat stick limit type of things) and seen more gear fail to retract or door sequencing issues than in my first 9yrs in the airplane.

Cheers,

Cap-10

I regularly fly the second and third jets (E2 and E3) for flight test work (E1 is on permanent loan to Boeing for their development work). They're now at about 4k hours each, which is half of what most of the CAF fleet has. Without having the depot's data in front of me, I'd say the majority of the Strike's age issues now are avionics and subsystem issues (as Cap-10 said). Thankfully, I haven't seen or heard of any fatigue issues that would cause us to trash an airplane. We escaped the longeron fatigue issues that plagued the light greys several years ago. With money invested in the right systems, I think the aircraft will be capable until 2035.