CV-22 down off the coast of Japan

[uhhello]

The actual AIB

231129, AFSOC, YAKUSHIMA JAPAN, CV-22, AIB REPORT.pdf

Edited August 2 by uhhello

[uhhello]

If all the issues the MA experienced before the actual causal issue are 'normal', thank god I never ended up on that aircraft.  

During takeoff from Yokota AB, the MA experienced the first EP of the mishap sortie (MS), "MISSION CMPTR 1 FLT" (Tab DD-47). This occurs, due to a software glitch, when the backup computer automatically takes over while the primary computer restarts, referred to as a ''warm-start" (Tab DD-47). This EP was displayed visually on the CDU and audibly with a master caution tone and necessitated the MC to complete a 29-stcp checklist while flying to MCAS lwakuni, which was completed without issue

At lwakuni, after exiting the runway at taxiway F, the MA experienced a second mission computer warm-start (Tab 11-11). The MC verbally acknowledged the warm-start alert and continued via taxiway F2 to the hot pits, an area for re-fueling without shutting down (Tab II-11 to 11-12). When the aircraft stopped in the hot pits, the MSMA TS exited the MA to prepare for refueling operations while the MSMAFE ran the refuel checklist (Tab II-13). The MP monitored fuel flow while discussing departure sequencing and timing with the KC-130Js for air-refueling (Tab 11-18 to 11-20). The MCP and the MSMAFE ran the checklist for the second wann-start (Tab II-13 to 11-15). While refueling, the MA experienced a third warm-start, which caused the Intelligence Broadcast Receiver (IBR) connection to drop, a system required for the MC to receive intelligence information (Tabs DD-47, and II-15). 
During the time on the ground at MCAS Iwakuni and while the MP was coordinating mission events with other exercise participants, the MA experienced multiple system advisories, mostly associated with the wann-start, to include: a blade fold control unit periodic built-in-test failure, a Global Positioning System (GPS) receiver failure, an exhaust deflector fail, a radio-frequency jammer failure, and an infrared jammer failure (Tab II-14 to II-17). The MC also nearly over­filled a feed tank due to a ground refuel-defuel panel fail (Tab 11-17). While some of these additional failures were associated with the mission computer fault, they require additional crew attention (Tabs DD-47 and 11-14 to 11-17). 

Edited August 1 by uhhello

[Bigred]

On 8/1/2024 at 9:46 AM, Sua Sponte said:

Is a chip indicator on an Osprey a "land as soon as practical" or AC's discretion during a training mission?

I am surprised land as soon as practical was/is even an option. I would’ve expected it to have been either land immediately for imminent failure or otherwise land asap. 

[uhhello]

1 hour ago, Bigred said:

I am surprised land as soon as practical was/is even an option. I would’ve expected it to have been either land immediately for imminent failure or otherwise land asap. 

Land immediately has some very serious ramifications 

[Day Man]

1 hour ago, uhhello said:

Land immediately has some very serious ramifications 

more serious than 8 KIA?

[uhhello]

2 hours ago, Day Man said:

more serious than 8 KIA?

They should have never got to that point. The aircraft was telling them something was wrong for a long time.  Way before it should have gotten to a land immediately.  They skipped over multiple 'as practical' and 'possibles'.  

[busdriver]

Couple things for the non rotary folks:

Lights with no secondaries are not treated the same as lights with secondaries. 

Land immediately over water means you're ditching intentionally.

Transmission chip detectors have a fuzz burn function that tries to burn up the chip.  When that's active, it usually illuminates the chip light (it's completing the circuit).  I'm told this is not abnormal on an Osprey.  On a 60 it's pretty common on a new transmission, but not once broken in.  Repeated fuzz burn is not normal.

 

[contraildash]

busdriver's summary above is spot on.

I flew the CV for 12 years. I wouldn't say chip burns were a 'common' thing but a singular chip burn would be seen every so often. The only time I got multiple PRGB chip burns I turned home after the second one, had a third one on final, and subsequently MX found the gear box was chipped out. I was just doing local training, easy call to go home. I also flew over open ocean frequently and we would talk through various EPs that would suck (such as PRGB chips or a drive system failure). Overall, the general consensus was that unless we doing a no fail POTUS directed mission, don't fuck around with chips.

Another thing from this accident that irks me is the rosy path we were led down by bell/boeing. We were always told to 'look for secondaries' associated with gear box chips. Well come to find out, you will see secondaries....about 6 seconds before the gearbox fails. Looking back, the logic was flawed. Reading through a lot of helicopter gearbox class A's shows that they don't give a whole lot of warning, such as loss of oil pressure, typically less than 30 seconds. The V-22 has an emergency lubrication system, that 'should' provide up to 30 minutes of lube. But that won't help if the loss of pressure is due to a gear coming apart. You just don't know what is failing inside the PRGB....not that it matters.

Overall, I loved flying the Osprey. I firmly believe that if the Marana crash had not happened and set the political firestorm that was the V-22 program back then, people wouldn't be so emotional about the program as they are today. The safety record is smack in the middle of the pack.

Oh and let's not forget that CAT5 lists the CV-22 on his bio....funny....because he crashed one.