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Elite 1K Joined: Apr 26, 2004 Posts: 1198 Status: Offline

Hey Smitty,

Might be hard to explain to those not in the know about the broom and string. Have you ever tried to check those out from the tool crib?

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ahhh...never heard that before. That's more specific, and answers the question I had about why one droops and the other doesn't. Thanks!

Ahhhh, now that's the detailed info I was looking for. Now I see what you mean. Thanks!

johnwill wrote:

Habu, read what MechFromHell wrote, "electrically locked". I'm not certain, but I think the electrical lock works through the asymmetry brakes. That doesn't sound like a hydraulic lock to me.

Correct … the asymmetry brakes are an electrically actuated mechanical lock (fun to rig) designed to automatically shut the LEFs down if the flaps attempt to split.

Ah, so a mechanical lock as well. You crew dogs get all the fun stuff! Crazy Pilot

Habu wrote:

You crew dogs get all the fun stuff! Crazy Pilot

Of course … then there is the 100hr flap seal inspections, lubing the rotary actuators during phase, and to top it off (if you have a HI AOA jet @ EDDY) you have to do the 7-day PDU oil level check.

Enthusiast Joined: Jun 03, 2006 Posts: 49 Status: Offline

ohhhh I used to hate doing that, I think that had to be done on ole 79-0557??? or it was an 80. Either way that lil job sucked, right along with having to remove the backbone panel for the SI tapes EVERY flight. Was pretty fun trying to teach FNG's that had been so messed with when you tell them "you have to take out the dipstick to check the PDU oil" they would never believe you until you did it and showed them... Mr. Green

Yo ho!

Good to see Habu! Long time, man.

As the guy who learned a lot about how those things worked mechanically ...

The so-called rotary actuators are simple gears. They have basic cogs that engage the teeth on a tube that runs out from the main drive HYDRAULIC motor.

The rotary motive force is provided by a hydraulic motor in the fuse. The connection to the torque tubes is what came loose on my incident when the back-shop dudes didn't put in a "keeper pin" and the drive tubes separated.

The assymetric flap signals didn't work, as apparently the sensors were upstream of the actual torque tube running along the leading edge of the wing. So I locked the things using the switch. Bunted over until left LEF was 2 deg up, then hit the switch. Made less assymetric drag, plus kept the left LEF from moving all around. Hell, I was maxed out (almost) and didn't need more things changing.

***************

As far as the control surfaces, let's get this straight.

There are "finger locks" surrounding the actuator cylinders. In flight, with no hydraulic pressure to an ISA, the sucker will eventually LOCK when those things find the small groove in the piston/actuator tube/whatever you call it.

If you have the chance to find a Viper on the ramp with the tail drooping, just gently move the thing(control surface) up and it will lock when those finger doofers find the groove.

gotta go,

Gums wrote:

it will lock when those finger doofers find the groove.

I love it!

Hey Mech!

I don't know how to describe it with technical accuracy like you wrenchbenders.

All I know is there were these "claws" around the actuators and they were normally held open if there was hydraulic pressure to the ISA.

I didn't have to fix the things, I just had to fly them and trust you folks. heh heh.

I also brought back every one I got from the crew chief. Had three really bad episodes, but got them back to the parking spot. Ooooops, the landing gear deal was shut down at EOR due to massive hydraulic fluid coming outta one of the mains.

out,

Elite 1K Joined: Apr 26, 2004 Posts: 1198 Status: Offline

Don't feel bad Gums, sometimes we call things doofers too.

Gums wrote:

As far as the control surfaces, let's get this straight.

There are "finger locks" surrounding the actuator cylinders. In flight, with no hydraulic pressure to an ISA, the sucker will eventually LOCK when those things find the small groove in the piston/actuator tube/whatever you call it.

If you have the chance to find a Viper on the ramp with the tail drooping, just gently move the thing(control surface) up and it will lock when those finger doofers find the groove.

Can anybody else confirm this?

Only finger locked actuators on the Viper should be in the gear doors?

I push my stabs/flaperons up all the time so I don’t bump my head … few hours later they would droop again?

When you Arm the left/right or the rudder this is liquid lock?

A Viper in flight without hydraulic pressure is going to make the local news as a class A. EPU provides minimum A system pressure if motor stops turning? JFS can be used with PMG.

EPU quits (includes bleed air mode) or runs out of fuel … “bang-out” time Bro?

Or is this post a chain yanking session?

Gums
Are you sure about the stabs/flaperons? I know the leading edge will lock but like Vark said I never felt the other controls lock when I pushed on them.

Elite 1K Joined: Apr 26, 2004 Posts: 1198 Status: Offline

I think it is a liquid lock.

Salute!

Well, hell!

I only did the trick on Block 1, 5, 10 and 15's.

Could it be that they changed the ISA's?

We have to find a Guard unit with really old jets to try this out. But I can tell you that i showed this feature to student-studly when we got to the jet and a horizontal slab was drooping. i did this to show him what would happen if he lost all hydraulics to the ISA.

The lock was mechanical, and you could feel the thing when it locked.

The LEF asymmetric brake was upstream of the "rotary actuators" and the main drive torque tube, so I had one LEF up at 60 degrees or so and the other one on left wing was moving all around. Remember that the right wing torque tubes were disconnected from the drive unit. Go look at the thing. Open the inspection door and see where the hydraulic drive tube connects to the tubes that operate the LEF's.

You can talk about all the back-ups, but the power supply fiasco for FLCS still bugs me. See my post about the B-2 crash.

Meanwhile, we're looking for some help from a troop that has older jets.

Gums sends ....

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Ok so LEFs, how are they actually operated?