Cargo Door Lock

[arcticblades]

Hello, I was a crew dog on a C-130 for 15 years...anyways, we're having a debate at work about the cargo door (I'm a C-17 crew dog now). Some of the fella's i work with think the C-130 cargo door is only locked in the closed position with pressurization. I worked on 130s that had a snubber infront of the actuator so i'm not sure if it's the same on all 130's or just the ones with the snubber, but I remember having to replace the spring on the cargo door lock latch mechanism on the side of the cargo door, that can only be unlocked by either A. operating door normally with hydraulics. or B. manually opening the cargo door...or C. if you climb up and pull up on the cables just behind the actuator you could unlatch the locks that way. long story short, anyone have any insight on these locks....do some c-130's have no latches and only the use acft pressurization to keep the door closed? I have $100 bucks on this one, but i'm pretty certain you cannot open the cargo door with these locks engaged... the cable is linked to the actuator so the locks automatically unlatch when the door is operated normally...but say you take out the actuator and then try to lift the cargo door using the come along....door isnt going anywhere unless you unlatch the locks on the side...or am i missing something?

[arcticblades]

btw, if anyone could post a pic of the lock, that would be most helpful =O

thanks,

[arcticblades]

me again =)

since i'm at a C-17 base, i no longer have access to a C-130 job guide, if somewould could please post a shot of the job guide of the page that talks about disengaging the locks prior to removing the actuator that would be most helpful lol

thanks

[tinyclark]

This pretty much explains the downlock system, so yes, there is one.

[arcticblades]

Thank you, that's exactly what i was looking for =)

i'm curious if this is on all c-130's or if it's only on certain ones...i see that is out of the H...i worked on the E models and it had them, but i'm not sure about others.

[Dan Wilson]

I know that E and H are the same in this.

One thing thats not really clear in the picture is, the door actuator is hooked to a dogleg thingy on the door and when you select "Open" on the cargo door it moves the dogleg thingy to actuate the locks open so the door can open.

Now H models and HC/MC-P aircraft have a dual actuator, not sure why the H had them but the rescue/spec ops birds have them because of the increased weight of the door and what is supposed to be stored in the door.

Okay guys, let the beating start on what I'm wrong about

[Railrunner130]

72-1288 was the first to have dual snubbers. I believe the purpose of the second snubber was to force the door down, not to lock or pressurize it.

[Dan Wilson]

The dual snubber's were installed to fix the problems with the doors that had a single snubber, and the damage caused by single snubber when you took the cargo door switch straight to closed.

On E-Models you always had to go to open for a second or two before going to closed, otherwise you stood a chance of ripping out the uplock.

As for the specific systems knowledge on how dual vs single works...brain is empty at the moment, if it pops into my head I will put it up here.

Dont mess with your brain, the results power sucks:mad:

[bischoffm]

Here is some helpful trivia on cargo doors acutators and snubbers

[Guest]

I was on the initial flight tests for the MC-130E High Speed Low Level Aerial Delivery System (HSLLADS). The engineers learned and modified as they saw what was needed to open the ramp and door at speeds up to 300 knots. By initial design, reinforcement had been added to the exterior surface from F.S. 737 to F.S. 1041 (from aft of the paratroop doors to the horizontal stabilizer).

When we first attempted (high speed) opening of the ramp and door simultaneoulsy, the cargo ramp would begin to open, but the door was held down by the negative airflow pressure outside until the ramp protrusion into the airstream created a burble in the airflow; then the door would "pop" upward, causing damage to the single actuator and the actuator attach point.

So the fixes that were incorporated were:

1. to put in a sequence switch so that the door did not attempt to open until the ramp was 15 degrees open

2. Install dual actuators on the cargo door

3. Add special buffer boards on the cargo ramp

That was in 1968 for the Talon 1s, and basically the same design was later incorporated on the Talon 2.

John

[Old Talon 1 F/E]

If I remember correctly the buffer boards had nothing to do with the High speed ramp and door. Their purpose was to keep the air flow to a minimum to keep the lift line, bomb line and saftey harness' from getting tangled up. They were flimsy and had nothing to do with stability.

[tinyclark]

I know those things didn't keep the ARN14 VOR receivers from shaking their vacuum tubes loose.

[Guest]

If I remember correctly the buffer boards had nothing to do with the High speed ramp and door. Their purpose was to keep the air flow to a minimum to keep the lift line, bomb line and saftey harness' from getting tangled up. They were flimsy and had nothing to do with stability.

The buffer boards have gone through several design changes over the years, and I wouldn't call today's design flimsy; but in the initial evaluation of HSLLADS, the airflow (negative pressure) that affects raising the cargo door was stabilized by the buffer boards, i.e., there was a noticeable difference with/without the buffer boards in place. They also help with other ramp activities such as Fulton Recovery.

[Old Talon 1 F/E]

Strange............My LTM 1MC-130E basic date 1 Oct. 81 change 3 dated 1 Dec 83 states and I quote;

"Buffer Boards

Buffer boards are installed on each side of the ramp. The buffer boards are designed to deflect the air around the ramp area during aerial recoveries and recovery kit drops."

This doesn't sound like a by-product of hsllds.

The same -1 also states the airspeed limit is 250 kias for ramp and door. It may have been tested at something higher but the limit stated in numerous places is 250 kias.

[yawdamper]

The single door uplock was also replaced by two uplocks evenly spaced from the centerline in the dual actuator configuration.

[P3_Super_Bee]

The single door uplock was also replaced by two uplocks evenly spaced from the centerline in the dual actuator configuration.

Yep, "J" models are this way.

[keepemflying130]

also any doors with flare/marker launcher mods. And, I have seen many versions. I don't think there are any dual snubbers out there. I think the previous post was in reference to dual actuators with no snubbers. No problems...a few zzzz's and a few beer'ssss since then. All good.

[Wombat]

I was on the initial flight tests for the MC-130E High Speed Low Level Aerial Delivery System (HSLLADS). The engineers learned and modified as they saw what was needed to open the ramp and door at speeds up to 300 knots. By initial design, reinforcement had been added to the exterior surface from F.S. 737 to F.S. 1041 (from aft of the paratroop doors to the horizontal stabilizer).

When we first attempted (high speed) opening of the ramp and door simultaneoulsy, the cargo ramp would begin to open, but the door was held down by the negative airflow pressure outside until the ramp protrusion into the airstream created a burble in the airflow; then the door would "pop" upward, causing damage to the single actuator and the actuator attach point.

So the fixes that were incorporated were:

1. to put in a sequence switch so that the door did not attempt to open until the ramp was 15 degrees open

2. Install dual actuators on the cargo door

3. Add special buffer boards on the cargo ramp

That was in 1968 for the Talon 1s, and basically the same design was later incorporated on the Talon 2.

John

Didn't they also fit dual door up-locks, one fitted either side rather than on center?

Wombat

[Guest]

I have to honestly say that I don't remember the dual uplocks as part of HSLLADS. I do believe the Talon 1's had the dual uplocks installed, but don't recall them being part of the mod.

John

[yawdamper]

Didn't they also fit dual door up-locks, one fitted either side rather than on center?

Wombat

Look at my post 3 up from yours, Dual actuator installation on the door includes dual uplocks, they are married together and you may begin to see AUX system reservoir modifications to alleviate pump cavitation during high altitude operations.

[Old Talon 1 F/E]

Reservior size had nothing to do with high speed ramp and door. That was the result of the installation of the Sargent Fletcher pods. They use a large volume of hyd fluid for operation. Prior to that mod the aux reservior size was the standard 3.4 gal, Fulton or non Fulton equipped.

[yawdamper]

Reservior size had nothing to do with high speed ramp and door. That was the result of the installation of the Sargent Fletcher pods. They use a large volume of hyd fluid for operation. Prior to that mod the aux reservior size was the standard 3.4 gal, Fulton or non Fulton equipped.

Operation of the cargo door at high altitude has been known to be difficult at times. Dual actuator has not changed this and I agree HARM mandates a larger reservoir (AUX is backup system). I was not saying dual actator comes with a larger reservoir but instead that you may see changes to the AUX (configuration), due to cavitation of the pump at altitude. A larger reservoir alone will not solve this problem, but configuring the reservoir, suction line and pump can solve it. It was just a side note as it pertains to the doors operation.

[Dan Wilson]

I cant seem to remember the danged HAR panel, I searched for a pic but couldn't find it but I did find some pretty nice links while looking.

Here's a NATOPS that covers refueling just about every thing they have.

http://www.everyspec.com/MIL-HDBK/MIL-HDBK+(0800+-+0999)/download.php?spec=MIL_HDBK_844A.1991.pdf

Here is the 129ths welcome book and it has some really really good photos some of you would like.

http://www.129rqw.ang.af.mil/shared/media/document/AFD-090609-023.pdf

[Guest]

At the time we put the Aerial Refueling Pods (Sargeant Fletcher) on the first six Talon 1s, the 7.5 gallon hyd reservoirs were not readily available, but there were lots of 5 gallon reservoirs available. So, we cut out a measured center section of one 5 gal unit, then cut another in half, and inserted (welded) the center section; plus a new glass tube and scale for the quantity indicator. As far I know, they are still installed.

Trivia crap---how many 5 gallon hydraulic reservoirs are on (some) Talon 1s?

[Skip Davenport]

At the time we put the Aerial Refueling Pods (Sargeant Fletcher) on the first six Talon 1s, the 7.5 gallon hyd reservoirs were not readily available, but there were lots of 5 gallon reservoirs available. So, we cut out a measured center section of one 5 gal unit, then cut another in half, and inserted (welded) the center section; plus a new glass tube and scale for the quantity indicator. As far I know, they are still installed.

Trivia crap---how many 5 gallon hydraulic reservoirs are on (some) Talon 1s?

3 :)