F-35 accident Fort Worth 15/12/22 - pilot ejected ok
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Not familiar with the specifics of the F135 engine, but it's standard design practice on jet engines that the high-pressure fuel doesn't only go into the burner - it's used as muscle for various actuators such as variable vanes and bleeds, etc. - so lots of fuel lines snaking their way around the engine. Typical pressure downstream of the fuel metering unit is around 300 psi - so any crack in a fuel line is going to result in a large fuel leak - not only do you have a big risk of fire if a line fails, you lose muscle pressure to the various actuators. In other words, bad things are likely to happen.
Smoke (or flames) is a pretty common indicator...
Smoke (or flames) is a pretty common indicator...
"...The F-35B 3BSM consists of a STOVL LOAN and a three-bearing swivel mechanism. The mechanism can deflect the exhaust flow through 95 degrees in the pitch axis and ±12.25 degrees in the yaw axis as a function of pitch angle. The 3BSM can vector up to 23,900 pounds of thrust at the maximum rearward thrust split. The 3BSM forward (No. 1) bearing is powered by twin fueldraulic actuator motors through a gearbox and drive train. The middle (No. 2) bearing is likewise powered by a twin fueldraulic actuator motor and gearbox/drive train system. A transfer gearbox links the middle and aft (No. 3) bearings with an efficient, compact, epicycle gear train. The twin actuator motors on the No. 1 and Nos. 2 and 3 bearings, respectively, are designed with a fail-degraded capability (full torque, half rate).This is one of the key differences between this design and that of the X-35B. In the X-35B, the Nos. 2 and 3 bearings were braked following a first failure, with no ability to continue vectoring the aft thrust post. This did not satisfy operational requirements requiring an ability to perform a shipboard vertical landing following a first failure. The dual redundancy on the fueldraulic motors enabled that fault tolerance on the F-35B...."
https://www.lockheedmartin.com/conte...y_Overview.pdf
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03 Jan 2023 John A. Tirpak | "...An Air Force spokesperson said that a “small number” F-35As in USAF service are grounded until a technical compliance/technical directive is completed. While she did not provide details, a TC/TD usually means that a part or system must undergo inspection, and if a problem or faulty part is found, be replaced. A government source said the problem seems to be engine-related, and so far, only jets with “a few dozen” flying hours or less are being inspected for the problem. “The scope and duration” of the effect on the USAF F-35A fleet “are to be determined based on additional ongoing analysis,” the Air Force spokesperson said. She did not say how many F-35As are affected, or whether they are in a single unit or dispersed across the combat air forces.” https://www.airandspaceforces.com/30...eliveries-dip/
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New F-35 engine deliveries suspended amid ongoing investigation 05 Jan 2023
"WASHINGTON — The U.S. military and defense contractor Pratt & Whitney have suspended deliveries of new engines for the F-35 fighter in the wake of a December mishap on a Texas runway. The F-35 Joint Program Office said in an email to Defense News that the delivery of new F135 engines was paused Dec. 27, after what the JPO described as a “mutual agreement” involving itself, the Defense Contract Management Agency and engine-maker Pratt & Whitney....
...The JPO said in a statement last week to Defense News it had issued guidance restricting some higher-risk aircraft from flight operations while the investigation continued. The JPO later revised its statement to say it had recommended the flight operation restrictions until procedures are developed for their return to flight...." https://www.defensenews.com/air/2023...investigation/
"WASHINGTON — The U.S. military and defense contractor Pratt & Whitney have suspended deliveries of new engines for the F-35 fighter in the wake of a December mishap on a Texas runway. The F-35 Joint Program Office said in an email to Defense News that the delivery of new F135 engines was paused Dec. 27, after what the JPO described as a “mutual agreement” involving itself, the Defense Contract Management Agency and engine-maker Pratt & Whitney....
...The JPO said in a statement last week to Defense News it had issued guidance restricting some higher-risk aircraft from flight operations while the investigation continued. The JPO later revised its statement to say it had recommended the flight operation restrictions until procedures are developed for their return to flight...." https://www.defensenews.com/air/2023...investigation/
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Fix coming for F-35 engine problem that froze fighters’ deliveries 11 Feb 2023
https://www.defensenews.com/air/2023...rs-deliveries/
https://www.defensenews.com/air/2023...rs-deliveries/
From Aviation Week
The F-35 Joint Program Office (JPO) has issued a directive recommending that all Pratt & Whitney F135s powering the global fleet of Lockheed Martin F-35s be retrofitted within 90 days with a fix for a vibration problem that caused an aircraft to crash on Dec. 15.While no flight restrictions are included, the JPO Time Compliance Technical Directive (TCTD) instructs immediate compliance “for the small number of aircraft that were restricted from flight.” No details have been released about what the retrofit involves, although the JPO says it can be performed “at the operational level and can be completed in 4-8 hr.”
Pratt & Whitney developed the retrofit procedure to mitigate harmonic resonance that was uncovered as the likely cause of the December mishap, which involved an F-35B during a predelivery check flight at the company’s Fort Worth production site.
Described by the engine-maker as an extremely rare phenomenon, the vibration problem is potentially common to the F135 variant powering the F-35B short-takeoff-and-vertical-landing model as well as the versions powering the conventional-takeoff-and-landing F-35A and F-35C models. Jennifer Latka, vice president for F135 programs, says there were no differences in the build standard of the engine involved in the accident or in that of the other small population of aircraft affected. “And we can all say with certainty that it was not a manufacturing or quality issue,” she adds.
While only a small number of aircraft were affected by the harmonic resonance, “the plan is to retrofit the entire fleet, because the retrofit is inexpensive, nonintrusive and supports the JPO’s desire to maintain and manage a single configuration across the entire fleet,” the program office says. “The JPO will work with the military services and international partners to ensure understanding of the TCTD. The safety of flight crews is the JPO’s primary concern.”
The JPO said Feb. 24 that it had cleared Pratt & Whitney to resume delivering engines, but Lockheed Martin has yet to resume deliveries of new F-35s. More than 850 F-35s have so far been delivered globally.
The F-35 Joint Program Office (JPO) has issued a directive recommending that all Pratt & Whitney F135s powering the global fleet of Lockheed Martin F-35s be retrofitted within 90 days with a fix for a vibration problem that caused an aircraft to crash on Dec. 15.While no flight restrictions are included, the JPO Time Compliance Technical Directive (TCTD) instructs immediate compliance “for the small number of aircraft that were restricted from flight.” No details have been released about what the retrofit involves, although the JPO says it can be performed “at the operational level and can be completed in 4-8 hr.”
Pratt & Whitney developed the retrofit procedure to mitigate harmonic resonance that was uncovered as the likely cause of the December mishap, which involved an F-35B during a predelivery check flight at the company’s Fort Worth production site.
Described by the engine-maker as an extremely rare phenomenon, the vibration problem is potentially common to the F135 variant powering the F-35B short-takeoff-and-vertical-landing model as well as the versions powering the conventional-takeoff-and-landing F-35A and F-35C models. Jennifer Latka, vice president for F135 programs, says there were no differences in the build standard of the engine involved in the accident or in that of the other small population of aircraft affected. “And we can all say with certainty that it was not a manufacturing or quality issue,” she adds.
While only a small number of aircraft were affected by the harmonic resonance, “the plan is to retrofit the entire fleet, because the retrofit is inexpensive, nonintrusive and supports the JPO’s desire to maintain and manage a single configuration across the entire fleet,” the program office says. “The JPO will work with the military services and international partners to ensure understanding of the TCTD. The safety of flight crews is the JPO’s primary concern.”
The JPO said Feb. 24 that it had cleared Pratt & Whitney to resume delivering engines, but Lockheed Martin has yet to resume deliveries of new F-35s. More than 850 F-35s have so far been delivered globally.
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https://schultzairshows.com/wp-conte...-card-2019.pdf (3.6Mb)
The Martin-Baker arm restraints entered service in the early 1970s and were standard equipment on the Tornado from first flight (1974?). They have been adopted to many other types since then, including the current RAF fleet of Hawk T2, Typhoon and the aforementioned F-35.
You have to respect the forceful summer breeze:
You have to respect the forceful summer breeze:
