The TH-57 Perpetual Motion Machine

[RobLyman]

I always thought the time delay was the time it takes the B/U pump to spin up enough pressure to pressurize the system via the shuttle valve. (Not for the electrical system to actually swap anything over.) My understanding of the system (in navy birds at least) is that the transfer module contains a spring loaded valve so that when Pri pressure drops below the limit, the shuttle is automatically moved by the spring and lack of pressure to allow the B/U system to power it.

One of the reasons we kept going back and forth in NATOPS procedures on when to move the B/U Pump to Auto vice On or Off was that some genius suddenly thought that we might be wearing out the shuttle valves on startup during that transition phase where the main pumps were still building up pressure and the B/U pump was running, thus giving the potential for the valve to flutter or some such.

To clarify, the delay is actually in the depressurization valve. The electrical relays and #2 logic module determine when the depressurization valve should stay open for 3-5 seconds, allowing the backup pump to come online and to protect the current limiters when neither main generator is online.

Regarding the transfer module, what you said is mostly true. However, the transfer to the #2 T/R servo happens a little differently, since it operates independently of the secondary shuttoff of the #1 transfer module (which is the #1 T/R shutoff). If you remember, the #2 T/R servo is on the deck of the hydraulics bay aft of the primary servos and to the right of centerline. It is totally separate from the utility module and the #1 transfer module.

 

[MasterBates]

AGGGHH!! You are making the LAMPS in my brain come back!

 

[bert]

Still bottom it. When we went to no-rotorbrake starts, they initially told people to do the 1" because that's how the Army does it. As it turns out (so I was told), the Seahawk has a more negative pitch than a BH at full-down. The result of doing the 1" was that we started throwing anti-flaps across the line as they disintigrated. Now everything is full down, from start up to shutdown.

The negative pitch makes sense, but I'm guessing Bert would be able to confirm that.

All 60 blades (the Mike has new blades and I don't know what their twist is, but I doubt it is too different) have a -18 degree twist so "flat" pitch is a fuzzy concept. Not to geek out, but...

- All models have the same available degree of travel for the collective full down to full up, but it isn't all usable. In general, you will hit engine limits (hot or heavy), XMSN limits (cooler days) or retreating blade stall (trying to go fast at altitude). I haven't flown in 4 months and am too lazy to look, but I'm pretty sure one one of the FCF checks for Vh is to verify that the collective isn't at the limit of travel.

- Flat pitch is verified by the maintenance autorotation. The Navy could shift its chart to produce that "pushed to the deck" feeling, but there would be drawbacks - tip path at engagement and flight idle being the most obvious. You could compare Army and Navy auto charts to see how close they are, but even if they were significantly different I don't think that would be the reason. There are aircraft like the Merlin that consciously designed in negative pitch for holding to the deck (-3 I believe) but if our 60's did that I never heard it.

 

[Pags]

Not to geek out, but...

- All models have the same available degree of travel for the collective full down to full up, but it isn't all usable. In general, you will hit engine limits (hot or heavy), XMSN limits (cooler days) or retreating blade stall (trying to go fast at altitude). I haven't flown in 4 months and am too lazy to look, but I'm pretty sure one one of the FCF checks for Vh is to verify that the collective isn't at the limit of travel.

Good geekery as always. And you're correct about the Vh check. If PCR adjustments have gone too far you can hit the collective stops before Vh. Usually a good sign that the ADs need to go start over on the PCR adjustments and that your FCF will go another day.

Since this has thread has devolved into a 60 FCF discussion, here's a question that came up at work:
-How do you handle having different FCPs on the same FCF? I know the NAMP says the FCP should stay the same, but that should doesn't hold up to the reality of operations/other demands. At my previous command (HSC) if you didn't finish an FCF book the FCP would initial the steps he completed with the J-date they were done. If a step had to be repeated then multiple copies of a page would be put in to the book. FCF debrief sheet would contain steps completed and a passdown. There's been some discussion as to whether the book should be closed out each day and new book opened on subsequent days. What are the other 60 guys doing?

 

[MasterBates]

My 60 squadron did similar to what you described.
My E-2 squadron closed out and did a new book. Until I became QAO.

 

[BACONATOR]

I don't think we EVER have a single FCP complete an FCF. We just have the FCP who completed the step or vibes initial appropriately, and the continuation sheet filled out with a good passdown of notes.

 

[KBayDog]

At my previous command (HSC) if you didn't finish an FCF book the FCP would initial the steps he completed with the J-date they were done. If a step had to be repeated then multiple copies of a page would be put in to the book. FCF debrief sheet would contain steps completed and a passdown.

Same here. QA/Control/Ops tried to keep the same FCP on a bird until is was up, but sometimes "life" intervened into the best intentions of the NAMP. If the same FCP couldn't stay on a bird, we'd put the results in a passdown logbook in QA and/or have a turnover with the next FCP.

For the most part, though, it was a point of pride within the FCPs to turn Black arrows into Green arrows, so we tried to be scheduled appropriately.

 

[helolumpy]

-How do you handle having different FCPs on the same FCF? I know the NAMP says the FCP should stay the same, but that should doesn't hold up to the reality of operations/other demands. At my previous command (HSC) if you didn't finish an FCF book the FCP would initial the steps he completed with the J-date they were done. If a step had to be repeated then multiple copies of a page would be put in to the book. FCF debrief sheet would contain steps completed and a passdown. There's been some discussion as to whether the book should be closed out each day and new book opened on subsequent days. What are the other 60 guys doing?

Flying with 6 HS squadrons, we do what you described. HS-10 tried to do the "FCF pilot of the Week" plan but there was much complaining to Ops who relented.

Whether to change out a pilot or not has greatly depended on what the profile is and how much you have left.
In fleet squadrons I've seen pilots get tagged to finish a profile, especailly if there were only a few check left until your completed.

At the RAG, there are always FCFs and since different pilots have different quals (NATOPS, Stan, DLQ, goggles) you usually only got hit for the FCF for one day.
Of course we also did weekend FCF pilots routinely...

But when you are doing ground turns for 2-3 days (HS-10 this happened once or twice a quarter) having the same pilot in the cockpit is cruel and unusual punishment!

 

[Pags]

I don't think we EVER have a single FCP complete an FCF. We just have the FCP who completed the step or vibes initial appropriately, and the continuation sheet filled out with a good passdown of notes.

I'm guessing you're talking about a post-phase FCF. Otherwise, completely do-able especially for modified profiles that only take 20-30min of flight time.

Thanks for the input gents. Does anyone have any sort of written guidance on this practice? I've been working my fleet contacts, but no one seems to have anything written, it's just common gouge.

 

[Gatordev]

I'm guessing you're talking about a post-phase FCF. Otherwise, completely do-able especially for modified profiles that only take 20-30min of flight time.

Thanks for the input gents. Does anyone have any sort of written guidance on this practice? I've been working my fleet contacts, but no one seems to have anything written, it's just common gouge.

I can't remember how we handled it back when I was JO on the West Coast, but I think we had some sort of Wing guidance for how we were supposed to do things on the East Coast. Basically, FCP would do what he could. At the end of the day, he would close out a cover page, along with all the QARs. The next day, if it was the same guy, you started a new section on the cover page and continued. If it was a different person, they signed the opening (and closing) sections of the cover page (again, along with the QARs) and would look through what was N/A'ed and what was done. In my last squadron, since I was doing the majority of FCFs for a year, my name was all over everything, but if someone else started one, I'd look over some of the more important numbers (like ETF). Also depending on who the FCP was, I might go completely through the book and proof stuff (and usually find stuff that was jacked up for one particular person). I didn't have a flying QAO, so I ended up proofing books a lot of the time anyway.

I haven't done a FCF back here on the West Coast yet, so not sure how this wing is running things.

 

[RobLyman]

In the Army, you "own" an MTF until it is complete. If there is prolonged troubleshooting, the same MTP stays with it until it is complete, but might, in a rare circumstance, turn it over to a more senior or experienced MTP if they need help. This helps reinforce systems knowledge for the MTP and gives him skin-in-the-game for doing it right and efficiently. It also keeps one MTP from doing all the ground stuff and then losing the flight time to the next MTP. MP time in the logbook is important for progression to MTP Evaluator qualification.

In our unit, MTPs give up some day-to-day flying in order to accomplish MTFs and ground runs, but in the long run, having the qual opens the door for other opportunities such as detachments, aircraft deliveries, etc... As a full time MTP/ME, I am usually in the top 2-3 pilots in flght time.

MTPs lead the troubleshooting in Army maintenance. If a pilot writes up a discrepancy, the producton control supervisor consults with an MTP, usually the senior MTP, on trouble shooting steps. The MTP follows the issue until it is fixed. He can't go to his ground job and leave it for someone else to work on, because it IS his ground job...not just a collateral duty. If there are other pressing things for the MTP to do, the aircraft status stays the same (red x or down) until the MTP gets back on task.

 

[KBayDog]

He can't go to his ground job and leave it for someone else to work on, because it IS his ground job...not just a collateral duty.

You have just described Utopia.

 

[HokiePilot]

I actually had a Tail Rotor Switch to Backup Control about two weeks ago. We were in a coupled hover when we felt a very solid shudder. The caution panel showed everything you would expect. I don't remember yawing that much. Less then 10 degrees. We quickly departed and headed for mom. To make matters more fun. We soon got a Engine Chip Light. It turns out there was a faulty pressure sensor.

 

[KiowaDriver]

Thread jack~ oh wait, maybe thread back to track:

Sometimes flying the ~57 at night, IMC, over water, I think to myself- damn, one engine. Sweet!

One engine keeps the EPs nice and short.

 

[jt71582]

I actually had a Tail Rotor Switch to Backup Control about two weeks ago. We were in a coupled hover when we felt a very solid shudder. The caution panel showed everything you would expect. I don't remember yawing that much. Less then 10 degrees. We quickly departed and headed for mom. To make matters more fun. We soon got a Engine Chip Light. It turns out there was a faulty pressure sensor.

I had something similar happen last week. Not in a coupled hover, but on short final to a spot here at NRB. Solid shudder, maybe a 5-10 degree yaw.