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  #1  
Unread 05-29-05, 09:25 PM
big al 08 big al 08 is offline
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oh! crap

if you lower the he gear and it only trails so you pump the hand pump and it gets really hard after three to four pumps,
usally it tales 20 to 30 cycles to get very
hard.???????????????? SO what is amiss?

Last edited by big al 08 : 05-29-05 at 09:27 PM.
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  #2  
Unread 05-31-05, 01:49 AM
SkyKing SkyKing is offline
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A real 'Boner'...

I guess you made it back to the ground in one piece? Sounds to me like the gear pack isn't toggling back. On the ground does it make a quick Zzzziip sound when you hit the master as it repressurizes? What I usually do on the ground is pull the CK breaker for the gear with the master off, pump the gear doors down with the floor handle for a look-see... then with the CK breaker still out, throw the master to the on position... which toggles the valve... then pump the gear doors back up to their closed position. What year is your P? Didn't some of the earlier models, like '73 through '75, come from Wichita without the extra pressurizing gizmo over the mains? Seems they added that later on, but I might be wrong... anyway... if yours has that particular item, maybe it's lost its charge???

SKyKing
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  #3  
Unread 05-31-05, 08:24 PM
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skymstr02 skymstr02 is offline
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I beleive that the extra "gizmo" is an accumulator.
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  #4  
Unread 05-31-05, 10:35 PM
big al 08 big al 08 is offline
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it's a 73 and just had it on jack and it workd fine for about ten times. the reason on the way home selected the gear up with no response, except the gear/stall horn went of maybe twice and quit. so returned to yuma and had them look at it, with no luck (worked fine on jacks).
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  #5  
Unread 05-31-05, 11:14 PM
SkyKing SkyKing is offline
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Sols?

Yah... that's the gizmo, ye old accumulator. Does anyone know when Cessna added it into the line?

Well Rick, your no-worky-gear on takeoff might be the squat switch up front not closing, or a break in the wire since that particular components wiring gets a work-out... hows the strut pressure. Sounds like this developed 'after' your log rolling incident. Did you hit a log with the gear at all? Could be a simple electrics problem in the LDG Gear lever-switch. Or the solenoid valves on the power pack not working right... when'd you last clean/service them?

We had a similar problem on our '77... called for gear-up on takeoff, the motor started but nothing happened. After cleaning the solenoids everything has worked just fine.

SkyKing
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  #6  
Unread 06-01-05, 07:19 AM
Dave Underwood Dave Underwood is offline
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My parts book says that accumulators were installed in all 1973 thru 1980 P Series Aircraft.

A small suggestion on testing the gear. Use some resistance like a hand or two on each gear leg or tire to ensure you are getting full pressure to overcome any airloads etc.

Why? If the seals start to fail internally, the gear may pass the extend and retract timing tests, but may not be able to extend fully against the airloads. If you are able to slow or stop the extension, it might be a good idea to get the seals replaced.

BTW if the above failure happens, you will not be able to pump them down either. A gear up is the only safe option left and that is going to be messy even at the best.

We have added that little test to all our gear swings just to be sure.
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  #7  
Unread 06-01-05, 02:30 PM
big al 08 big al 08 is offline
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skyking, did or i think i did your instruction as per and the gear doors would not pump up (do i need to select the up position first?) nut they pumped down, they returned to the up position with the cb and master on. also slowed down to 80 when i was cycling the gear the second time when they extended. i have had this happen before, except for the pummp handel becoming very still with only 2 or 3 pumps. thanks
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  #8  
Unread 06-01-05, 03:55 PM
SkyKing SkyKing is offline
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Procedure...

Let's go through this one more time... and this is a procedure I use on the ground during pre-flight. You DO NOT move the Landing Gear selector handle... it stays in the down & locked position with the green light.

When you enter the cabin to check fuel gage indications, the moment you hit the master switch -- assuming the LDG GEAR MOTOR circuit breaker is pushed-in -- you should hear a quick "Zzziip" of the power pack as it repressurizes from any leakdown over a few days or if temps have dropped. This tells you the powerpack motor is functioning and that it is pressurizing the system. At this time you can also check the landing gear lights with push-to-test and on the gear-down-green light, you should also get the unsafe horn when pressing. Now, turn the master off momentarily and then recycle it to the 'ON' position again... and this time listen for the audible 'thump' of the solenoid shuttle valve in the powerpack.

OK, now turn the master switch 'OFF', pull-out the LDG GEAR MOTOR circuit breaker, then extend the emergency gear handle on the floor and pump down the doors. After completing an inspection of the actuators, hoses and anything else you might want to check in the undercarriage... and maybe even reaching through a hole on the left bottom side of the fuselage with your index finger just aft of the left main gear so as to feel for any fluid leaks/seeps along the rod and after lower part of the door actuator... go back to the cockpit and with the LDG GEAR MOTOR circuit breaker still in the pulled-out position, throw the master switch to the "ON" position and then using the emergency gear handle, pump the doors shut until resistance is felt. Stow the handle. Now, push-in the LDG GEAR MOTOR circuit breaker while the master switch is still on. If the emergencr gear handle properly re-pressurized the system, the power pack should remain silent when you push the circuit breaker back in. But if you didn't give it enough pumps on the handle, it could give a quick "Zzziip" as the powerpack brings it back to near 1500 PSI, or so.

Hopefully this detailed explanation will have clarified things. I usually use a clean paper towel around all of the accessible rods on the actuators, so if there's any 5606 juice, it will show red... and it keeps the fingers clean.

Also, while you're doing this routine, it's a good time to swipe a little 5606 on the nose gear strut to keep it clean and lubed... the seals will like you.

SkyKing
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  #9  
Unread 06-01-05, 05:18 PM
kevin kevin is offline
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Skyking,

Question: Why do you pump the doors closed, instead of pushing in the circuit breaker and turning on the master, and letting the power pack close the doors? What are you looking for with your procedure?

Thanks,

Kevin
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  #10  
Unread 06-02-05, 11:05 AM
big al 08 big al 08 is offline
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thank's boss!
will walk over this am and try it out.
should be able to get it as i printed it
out and if i can remember which way to
strip is located. (no my logging activities
didn't entail the gear)
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  #11  
Unread 06-02-05, 12:44 PM
big al 08 big al 08 is offline
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did exactly as you perscribed and all the results were what you said to expect. ok what does this mean? why when i tried to pump the gear down the hand pump became pressurized only after two pump cycles? does that mean the cyclling was out sync? or ? orginally when the gear trailed and the pump didn't work i recycled the gear and it came up, then selected down and got the green and landed okie dokie.
thank's rick
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  #12  
Unread 06-02-05, 06:49 PM
SkyKing SkyKing is offline
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Holy xxxx Batman!

Looking into crystal ball, I think it says, "Holy shit... I think I'm a candidate for a belly test!"

If what you're saying is true, I think you might want to forego any 'aerial logging operations' until you get those solenoids on the powerpack taken apart and cleaned. Remember, when you're buzzing around those puppies are getting warm... ergh, I mean HOT -- especially where you live and fly!... and any residual 5606 that entered inside where the plunger is located could get really nasty, like VERY sticky and prevent things from happening. Gee, I hope yours has the modified unit with the openable solenoids. Some of the '73 models didn't and there was a SB from Cessna to change them out... same thing with the little "T" item in the nose gear strut in the black cup with the spring, which can let the nose gear collapse. Oh boy, we're having fun now, no?

When you selected gear up or down, as the case may be when you had the problem, could you hear the gear motor running, or shall we say, G-R-O-A-N-I-N-G???

You might want to throw a pressure gage on the output side of the pump... there's a provision down near the dip-stick if you look and check the manual... to see if the pump is putting out the required presssure too.

SkyKing
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  #13  
Unread 06-02-05, 07:17 PM
big al 08 big al 08 is offline
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no groaning, must be stupid for i still do not undrstand why the hand pump would have almost total pressure bult up on it in tow or three pumps. flying north tomorrow will either take a shot on retraction or keep it a 336 until arriving at the maintenance shop in yuma, if i was sure the hand pump would work as it did today opening the doors up i wouldn't give a second shot. thanks rick
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  #14  
Unread 06-03-05, 02:27 PM
SkyKing SkyKing is offline
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Flow chart

You might want to lay out the service manual section on the landing gear and trace out the 'flow' chart of the hydraulic fluid from the emergency gear hand pump and see what all it interacts with... and whether electric power is applied or not insofar as shuttle valves and the solenoids... I don't have mine handy at the moment or we could walk through it. From that review you should be able to pinpoint why you're getting a hydraulic lock-up after two strokes on the pump... my sense is that something is not toggling, such as a shuttle valve in the power pack.

When's the last time you cleaned the solenoids on the powerpack? Pretty simple procedure that could save your belly... and your bacon!! GMAs went through the DO and DON'Ts on that sometime back... maybe it's still here on the web someplace.

Have you checked the fluid level of the 5606 to make sure it's topped off? There's also a fluid-acid test in the book. Don't forget to check for proper color of the contents. It's a good idea to look at what's on the dipstick with a bright light so that if there's any metal in the fluid it will show-up. How many hours on the powerpack since it was last overhauled/replaced? These ARE time sensitive items like the mags.

Lastly, I wouldn't go off into the wilde blue yonder without first determining where the problem is, because you might not be able to get green & locked... or even yellow and up-locked.

SkyKing
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  #15  
Unread 06-03-05, 02:35 PM
SkyKing SkyKing is offline
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Hand pumping

Oh, and Kevin... as to why hand-pumping the gear doors back up, first it gives you a chance to hear what's going on, throws fluid through the hand pump and lubes the seals, second it reduces one-cycle on the powerpack from wear & tear (like motor brushes), and thirdly it saves the ship's battery.

Those of us who aren't blessed with two hydraulic pumps have to take care of the only ONE we have... sort of like taking care of your heart!

SkyKing
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