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Recently, we had one of our Herc experienced rudder damage. the details are as follows:

the crew ground aborted a mission due to utility hydraulic fluid leak from Rudder booster package. once the trouble shooting was carried out, crew discovered a crack in rudder booster package because of which, utility hyd system quantity was completely lost. Now the crew had to wait for the part to arrive, which took about two and a half days ( less then 72 hours....55 hrs from the occurrence, to be precise). after receiving the requisite component for replacement, they found Rudder stuck on one side with extensive damage to the support structure and pivots of rudder. now my question is that how could this damage occur ??? while the aircraft was parked on Tarmac, the weather for the period of parking didnot had winds more than 22-27 kts. Also, the Booster hydraulic reservoir didn't had any fluid loss. it is also worth mentioning that the Utility side rudder boost SOV was kept close due to dripping fluid from the boost package. Also what would happen if somebody put the Booster side SOV also closed for Rudder ( as it is known that these SOVs are fail safe open when electric power is removed from the aircraft )

Please any one can explain me the following concerns:-

1. Can a combination of utility hyd loss from rudder booster package and winds of 22-27 kts can flutter the rudder to experience heavy damage. is there enough hydraulic in system lines to provide adequate dampening for flight controls.

2. if Rudder Booster SOV was put off, can it have a discontinuity in priming of Hydraulic fluid in the lines for flight controls. (As i presume the SOVs for booster package are fail safe, so the valves will be open when power is lost)

this seems to be a lenghty query, but i will appreciate a satisfying answer from experience crews, as there no dearth of it in this forum....cause its someone's NECK (Ass) on line !!!!

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"once the trouble shooting was carried out, crew discovered a crack in rudder booster package"

Where was (is) the crack?

The Rudder Boost pack has a common actuator so if the housing is cracked both systems can have issues.

With the boost shut off valves closed the pack (on the utility side) will have no fluid on either side of the actuator and therefore NO dampening capabilities.

The booster side should have dampening capabilities (as long as the actuator housing is not cracked through both sides) but it sounds like there is a path for the boost side fluid to also bypass or leak.

If you can move the rudder by hand (with little pressure) the booster side fluid has also been lost and internal leakage of your pack is indicated. (sounds like it can/will move based on the damage sustained)

As the rudder moves (with the shutoff valves actuated OFF) the replenishing valves will allow fluid to move side to side in the actuator to prevent a "locked flight control".

If both utility and booster shutoff valves were "OFF" and the actuator is leaking internally the booster side fluid would ALSO be lost and NO dampening capabilities for either side. This would explain your damage.

As for the ass on the line; an internal leak on a TANDEM actuator with loss of both systems fluid and resultant loss of dampening capabilities would be hard to pin on an individual.

If the leak is internal there would be NO indication of a leak on the booster side just the utility side.

A small internal leak (transfer of fluid) from the booster side could /would (did) take some time to happen, but the replenishing valve design would allow ALL of the fluid in the TANDEM actuator to be lost.

I guess it will depend on the extent of the crack. Gust locks are not a normal use item and I would think the rudder “felt” normal when the crew left the aircraft.

The only question I have is...

Was the fluid "STILL" dripping from the actuator with the utility shutoff valve closed?

I would say it WAS as I doubt the crew would "actuate" the rudder enough times to evacuate the TANDEM actuator of all utility fluid (and I would add it would NOT be advisable to do so as ANY fluid in the actuator would provide dampening capabilities) but once lost the rudder would move freely…..

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Thanks NATOPS1, the picture is getting clear, as for your question about the fluid"STILL" leaking with the utility SOV closed, i will get back to you.

Is there a reference which you can cite from the operating or maintenance manual, citing any action a crew should have done to keep the aircraft safer with the leaking boost package. Also, plz note the observed no leakage from the BOOSTER UTILITY reservoir and when they arrived back to aircraft (50-60 hrs). the BOOSTER UTILITY HYDRAULIC reservoir was intact. so how come there was insufficient SNUBBING for the rudder and the Damage occurred. The crew could not get a Hangar despite their efforts (at CYYT).

Will appreciate if you throw some more light into This??

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Also, plz note the observed no leakage from the BOOSTER UTILITY reservoir and when they arrived back to aircraft (50-60 hrs).

I can't say I have seen or read anything to back this up BUT... as the rudder moves only the fluid in the actuator would "leak" so I would NOT expect to see a reservoir reduction.

I would say the fluid in the reservoir cannot be transferred due to “suction” into the actuator in an amount that would (visually) reduce the fluid level.

I think the actuator housing has cracked in a manner that connected the Utility and Booster systems and caused a "single point failure".

FYI all, THIS is why the ELEVATOR has two SEPERATE actuators; to prevent a "single point failure"....

I have sent you a PM so check it out. Look in your TO for flight controls and see what your books say. (ours seems to be a bit contradictory...)

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1. If you had a complete loss of the utility system fluid it is highly likely that air was pumped through your boost pack effectively removing any remaining hydraulic fluid from your rudder boost pack. The utility side of the actuator snubbs your right side and the booster side snubbs the left. With the utility side blowing out it will not have sufficient fluid to snub the rudder from full right travel. It is possible that wind could cause damage but highly unlikely if it only got up to 22-27kts. My guess would be that the damage was done when someone was running the rudder through with no fluid in the utility rod end as the boost pack would come to a sudden stop without any snubbing action.

2. If the S/O/V is off it is off but once you lose power or turn it to the "Open" position. Once the pack gets to the point where it's leaking like crazy it doesn't really matter anymore if it is opened with the power off. The pack will drain itself anyway.

Just my 2¢

- If the pack was bad and leaked that much rudder gust locks should have been installed. I believe that there is something in the -6 about installing gust locks if the pack isn't primed with fluid but I am not at work to look this up.

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Not sure "that" is what the picture is showing....

TO 1C-130H-2-27GS-00-1

This is the version I have access to...


1-4 Change 5

1-7.4 Flight Control Wind Precautions.


Do not use mechanical restraining devices on flight control surfaces, unless both

the utility and booster hydraulic systems have been depleted or a booster unit has been

removed (aileron, rudder or elevator booster package). Built-in snubbing action in a fully

serviced system will prevent slamming of the controls into their stops.

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As for if there was anything the Crew could have or should have done, no there is nothing.

Outside of inflight, once it lands and is handed over to mx that's the end of their responsibility, even though on the road when we have had really high or gusty winds we have kept power on the plane with the suction boosts pumps on to keep the flight controls from slamming all over the place.

The built in gust dampening only last a little while in winds.

Parked with winds of 20 to 30 it is quite possible to see damage, with winds that high you can always get unreported gusts much higher than that.

I have seen planes in winds of that speed range that was slamming the controls back and forth so hard it would definitely risk your manhood to try and get into the pilots seats so a damaged rudder would be possible; though it seems like the damage you found is pretty damn extensive, it could be possible that there was some existing damage and this wx event just damaged the rudder further to what you have now found?

Edited by Dan Wilson
Kant spel
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