All things MV-22 Osprey

[hscs]

Very interesting read - read the whole report today. Having some sort of advisory / caution light for a chip detector activating its fuzz burnoff seems a bit odd (assuming that I read the report correctly) IMHO. OBTW - that's a lonely stretch of ocean from main islands to Oki.

 

[Roger_Waveoff]

To be clear, "[Any Gearbox] CHIPS" has always been Land As Soon As Possible in the V-22. The gray area has been when it's the "CHIP BURN" advisory. That decision has since been taken out of our hands.

 

[sevenhelmet]

To be clear, "[Any Gearbox] CHIPS" has always been Land As Soon As Possible in the V-22. The gray area has been when it's the "CHIP BURN" advisory. That decision has since been taken out of our hands.

I’ve never flown anything (that I know of) which has a “chip burn” feature. What’s the difference?

Curious what engineering was hanging their hat on with that one, and why the procedure would be different.

 

[phrogdriver]

I’ve never flown anything (that I know of) which has a “chip burn” feature. What’s the difference?

Curious what engineering was hanging their hat on with that one, and why the procedure would be different.

Because successfully burning a chip means the problem is not that bad. It basically categorizes chips by severity

 

[insanebikerboy]

I’ve never flown anything (that I know of) which has a “chip burn” feature. What’s the difference?

Curious what engineering was hanging their hat on with that one, and why the procedure would be different.

Chip burn exists in most large rotary wing aircraft. Can’t recall for the TH-57 and don’t know about other small helos.

Essentially, every rotating gearbox creates metal fuzz. The chip detectors are designed to burn off that fuzz but not larger pieces. In the helos I’ve flown that burn off happens without pilot knowledge, it’s the larger pieces that trigger the chip light.

I do find it interesting that there was essentially a chip burn advisory light. To me, anything gearbox related made me want to get on the ground quickly.

 

[number9]

Essentially, every rotating gearbox creates metal fuzz. The chip detectors are designed to burn off that fuzz but not larger pieces. In the helos I’ve flown that burn off happens without pilot knowledge, it’s the larger pieces that trigger the chip light.

I'm neither a pilot nor a mechanical engineer. Is the "burn off that fuzz" designed to burn the fuzz completely, or simply unblock the chip sensor itself?

I feel like you'd need quite a bit of amperage to actually turn fuzz into.. well, burned fuzz, I guess.

 

[ChuckMK23]

I'm neither a pilot nor a mechanical engineer. Is the "burn off that fuzz" designed to burn the fuzz completely, or simply unblock the chip sensor itself?

I feel like you'd need quite a bit of amperage to actually turn fuzz into.. well, burned fuzz, I guess.

Very common in mechanical gear box / transmission aviation applications - particularly in rotor-craft. Generally the system is capacitance based with the goal of burning off or "clearing" ultra fine particles that adhere to magnetic based detectors in the oil train/sump that are normal wear. larger metallic "chips" will not "burn off" and are an indication of a pending failure mode - either to the flow of lubrication or of the physical gear train itself. In either case these indications direct a Land As Soon As Possible at the least - and with secondary indications escalate to Land Immediately.

So we have the What and How but not the Why. I suspect a defect in manufacturing or overhaul life cycle will emerge as root cause. I would not be surprised if a redesign effort emerges given the advances in gear box technology since the original V-22 design was frozen.

Also it seems the PMO and the larger community kind of had the mindset that a catastrophic drive system failure was simply not statistically possible so why address it. That mindset and culture will certainly change.

AFSOC is the only operator without a crushing amount of skin in the game. If AF holds on to the platform, that will say something. If they dump it in favor of something else, that will be telling as well.

I wish @phrogdriver would add some insight here.

 

[number9]

Very common in mechanical gear box / transmission aviation applications - particularly in rotor-craft. Generally the system is capacitance based with the goal of burning off or "clearing" ultra fine particles that adhere to magnetic based detectors in the oil train/sump that are normal wear. larger metallic "chips" will not "burn off" and are an indication of a pending failure mode - either to the flow of lubrication or of the physical gear train itself. In either case these indications direct a Land As Soon As Possible at the least - and with secondary indications escalate to Land Immediately.

As always, Chuck, appreciate the info! Seems like there's a lot of nuance in the system and potential failure modes as well.

 

[sevenhelmet]

The concept of "burning off" metal chips in your oil is interesting, and not something I'd have intuitively thought was a good idea (e.g. let's shoot a bunch of electricity into an oil-soaked box full of moving metal parts!)

But I guess if it works...

 

[number9]

The concept of "burning off" metal chips in your oil is interesting, and not something I'd have intuitively thought was a good idea (e.g. let's shoot a bunch of electricity into an oil-soaked box full of moving metal parts!)

But I guess if it works...

I thought they were pieces in size of mm and above, and so was curious how it could be effective. But if it's smaller particles suspended in the oil, I could see how that works when they pass through the detector?

 

[VMO4]

Probably way out of my lane here, but I read the report and had two thoughts,

1) One day while in the back of a UH-1N over the swamps east of NOLA, we got a chip detector light, the pilot, who was also the CO and a Nam vet, spread his knees, picked out a dry spot through the chin bubble, and we landed. ...and

2) Boy the USAF can come up with acronyms for crew members besides the two guys sitting up front.

 

[JTS11]

I thought they were pieces in size of mm and above, and so was curious how it could be effective. But if it's smaller particles suspended in the oil, I could see how that works when they pass through the detector?

From a -53 perspective (3 engs and 2 Nose Gearboxes that fed the MGB) , if you got a chip light, you'd scan for secondaries (temps and pressures). If there were secondaries, you'd shut down that motor; if not, you'd pull and reset the CB to clear the fuzz and see if the light returned. If it did, and there weren't secondaries, you'd maybe take it to the nearest airfield, shut down and have the CC pull the chip detector and see what you're dealing with. If it's just a little fuzz, turn back up and ground turn it for 20-30 mins to see if it reappears. If not, press on. If so, depends on the situation.

Now, a little different with the essential transmission gearboxes (Main Gear Box, Intermediate Gear Box, Tail Gear Box). Any secondaries, you're landing immediately. Out over the water you're thinking ditch it, or if close to land, maybe get low and slow and try to limp it to shore. But, if no secondaries, you'd still pull and reset the CB. If it came back, it's land as soon as possible, shutdown, and have the CC pull the detector to see what's going on...call back to base if you can..if not, that's why we designate people aircraft commanders.

Just my observation from my (now a little dated) experience as a -53 dude flying a large, old helo.

 

[number9]

From a -53 perspective (3 engs and 2 Nose Gearboxes that fed the MGB) , if you got a chip light, you'd scan for secondaries (temps and pressures). If there were secondaries, you'd shut down that motor; if not, you'd pull and reset the CB to clear the fuzz and see if the light returned. If it did, and there weren't secondaries, you'd maybe take it to the nearest airfield, shut down and have the CC pull the chip detector and see what you're dealing with. If it's just a little fuzz, turn back up and ground turn it for 20-30 mins to see if it reappears. If not, press on. If so, depends on the situation.

Now, a little different with the essential transmission gearboxes (Main Gear Box, Intermediate Gear Box, Tail Gear Box). Any secondaries, you're landing immediately. Out over the water you're thinking ditch it, or if close to land, maybe get low and slow and try to limp it to shore. But, if no secondaries, you'd still pull and reset the CB. If it came back, it's land as soon as possible, shutdown, and have the CC pull the detector to see what's going on...call back to base if you can..if not, that's why we designate people aircraft commanders.

Just my observation from my (now a little dated) experience as a -53 dude flying a large, old helo.

Thanks for the detailed reply!

 

[Flash]

A couple of questions from a nonvertical lift guy, so excuse my ignorance.

- Land As Soon As Possible - The report noted a helo pad and a smaller airport closer than the airfield they chose to divert to, does helo/VSTOL land ASAP options usually take into account help pads? Is there comprehensive info on helo pad location easily available like airfields? Second part of question, is land ASAP put the aircraft down on any available spot or the closest pad/airfield? And is there a difference between 'Land ASAP' and 'Land Right Fucking Now!'?

- V-22 Single Engine? A quick search finds that the V-22 can fly single engine but has some limitations doing so, so why isn't shutting down the engine part of the EP for a chips light? Was a catastrophic failure not considered likely? Too risky? Or do you wait for secondaries like in the 53?

 

[wink]

And is there a difference between 'Land ASAP' and 'Land Right Fucking Now!'?

I don't remember there being a distinction in the Navy, but in the airline world there is "land as soon as possible" and "land as soon as practicable". The distinction takes into account your airfield options.