F-35B accident at Fort Worth

a reply to: vNex92

Hell of a lot better than the Su-57 will ever be.

Other than a burned out cockpit, and sitting on its nose, it's in really good condition all things considered.

www.military.com...

a reply to: Zaphod58
The ejection looked totally unnecessary to me. The aircraft pas pretty much down and stopped by then. It looked like the lift fan lost power. That might explain the smoke out of the tailpipe. I'm wondering if the drive shaft might have sheared and the engine went into overspeed and the computer shut it down.

a reply to: JIMC5499

The B uses an auto ejection system for hovering. It's programmed to eject if the aircraft goes out of control in the hover, once certain conditions are met. It looked like once the aircraft came back level, the computer decided conditions were safe and punched the seat.

a reply to: Zaphod58

I didn't know about that system.

It did give me a laugh though. Can you imagine being the pilot? You just had a wild ride, then the aircraft lands upright and stops. You're thinking "I'm going to walk away from this and then the ejection seat kicks you in the a$$.

a reply to: JIMC5499

It would be funny as hell to see the look of relief on the pilot's face, just as he disappears from the cockpit.

originally posted by: JIMC5499
a reply to: Zaphod58
The ejection looked totally unnecessary to me. The aircraft pas pretty much down and stopped by then. It looked like the lift fan lost power. That might explain the smoke out of the tailpipe. I'm wondering if the drive shaft might have sheared and the engine went into overspeed and the computer shut it down.

I had very similar thoughts.

But here's what I find curious: The plane descended at a steady rate in a horizontal attitude until all 3 wheels touched down almost simultaneously--obviously well controlled up to that point. It looked to me like the landing gear struts were not fully compressed during that first touchdown and they fully extended once the aircraft bounced briefly back in the air. That would suggest that the initial descent rate was within design bounds and the landing gear was not damaged during the initial touchdown. That would also imply that the aircraft structure around the landing gear was also probably not damaged.

The curious part is why the aircraft briefly bounced back into the air after that first contact. I don't think there could possibly have been enough energy stored in the compressed landing gear struts to cause that to happen. Plus, it looked to me like the aircraft was momentarily in level flight just before it nosed over. That means that it seems to have increased its lift right around the time it touched down that first time, otherwise it could not have flown off the ground again. I suppose it's possible that the aircraft could have gotten airborne again because it picked up a ground effect boost by being so close to the ground?

a reply to: 1947boomer

It sounded like the engine never throttled down, the entire time the event was going on. From what I've been told, as soon as the weight on wheels switch registers weight, the engine is supposed to begin throttling down. If it stayed at a constant power setting, then there may have been a bounce as the wheels touched down. At that point, either the pilot inadvertently pushed forward, expecting the aircraft to be settling to the ground, or the lift fan failed/throttled down, leaving all the power coming from the rear exhaust causing the aircraft to pitch forward.

a reply to: 1947boomer

That's why I'm thinking a failure in the lift fan drive shaft. The engine is at full power at landing, then the failure occurs. The engine loses the load from the lift fan, causing an overspeed that results in the engine having an increase in power lifting the tail of the aircraft.

I've seen the driveshaft fail on a Sea King helicopter. Fortunately it was on the ground at the time. Wen the load came off the Power Turbine section the exhaust of the engine almost tipped the helicopter on it's side. The pilot pulled both "T-handles" shutting off fuel flow to both engines. Then they sat and waited for the rotor to wind down.

It was apparently a USAF pilot working for the DCMA, on a DCMA flight before acceptance.

The JPO has issued a TCTD (Time Compliance Technical Directive), and grounded some newer F-35s. The Israeli Air Force has followed suit and grounded their F-35As. Anonymous sources are saying that a high pressure fuel line failed during the accident sequence. It's believed that aircraft with less than 40 hours time are affected.

www.defensenews.com...

A fix could be in place later this month to allow deliveries to begin again. There is a near term solution that will be put in place to allow deliveries to resume, before a permanent fix is applied. A permanent fix will require a combination of things to dampen vibrations in the engine. Once the solution is applied to new aircraft, it will have to be refitted to existing aircraft.

www.defensenews.com...

The JPO has issued a TCTO worldwide with the recommended fix for aircraft currently flying. The first aircraft to get it will be the ones currently grounded. Each aircraft will take 4-8 hours to complete.

www.defensenews.com...