Warbird Information Exchange

A while ago, a DC-3 stopped at the field where I was working, and I stopped by to admire it.

Loads of $$$ into the restoration. Polished aluminum. It looked gorgeous.

I noticed hydraulic fluid (red in color) seeping from fuselage skin laps underneath the cockpit. When the crew returned to depart a few hours later, I pointed out the leak, which had grown to at least a quart on the fuselage and about a pint on the asphalt. I assume it was brake related.

I am an A&P, and I offered to look at the problem and fix it, if it was minor, at no cost to them.

They rather impolitely blew me off, fired up, and departed.

So,

was this an inconsequential maintenance matter?

or was warbird arrogance rearing it's ugly head?

The DC-3 hydraulic system controls the gear, flaps, brakes, cowl flaps and windshield wipers.The main storage tank, accumulator and selector valves are all in the cockpit area ( some slightly different to others). The system has so many areas where it can leak that it could be near impossible to trace all. Some planes that have a "tight" system like ours was it is not too much of an issue, if you have a "leaker" then it is. The system is designed to be filled in flight, and this has been done regularly for the last 60 plus years. Your offer was most generous, almost lucky that they did not accepts as you could have been there for a couple of days!!. I would ask what type of flight was being performed. Things were a little different "back in the day" a leak was part of the job ( I flew night freight) and you tended to judge a leak on 1. how much spare fluid do i have, 2. how big is the puddle,3. how bad does the freight need to get there.
As we had a fully stocked tool box behind the main bulkhead, it was not uncommon to whip out tools and spend a couple of hours fixing stuff while enroute. On one occasion having taken off from Brownsville night IMC, we had a double generator failure climbing through 6 K. I had a YOung Jumpseater with us, his eyes went as big as saucers as i flew out of the left seat, yelled at him to vacate his position and hand me a slotted scredriver. While the FO turned off all equipment and notified ATC that we would be NORDO shortly, ( which by the way 30 mins of batt time is BS, we were lights out in 10). I pulled of the electrical panel, pulled the voltage regulator and went to town "flashing" the field. We were able to get one online, and after a brief stop in GTU to see if we could get the other one online, continued to YIP to deliver the freight.
One of the great things about a '3 is the way she "talks" to you through the hydraulic system after touchdown, you can almost hear fluid doing its thing. sights, sounds, smells, My DC3 hat is still stained from having to fill inflight and having a line blow and squirt fluid everywhere!!
Simon

_________________
"Never in the field of human conflict was so much owed by so many to so few"

I agree, Our goon leaks from the cowl flap controls, we put new orings in tighten it and after awhile it starts to seep. What looks like a blood bath may only be a tiny amount. It is a Royal pain in the @$## to track these leaks down.

Kinda like a Chinook ...if you see Hydraulic Fluid seeping everywhere...you can feel good that she'll fly ya to destination . If she is dry as a cob.. ..yer gonna have a precationary landing somewhere along the way .

_________________
Kind Regards,
Gary Lewis
J.A.F.O.

I can't remember for sure as I've only flown 3rd seat in the R4D once (so far), but I believe that there are at least 6 different points in the checklists where you verify the hydraulic fluid level. In addition we always do a couple of "for good measure" pops of the gear selector during longer flights to make sure the wheels are tucked up within the plane and are sure to isolate the system once we're up and going to try and keep from having any nasty surprises when something does let go one of these days. Our Maintenance Officer does an excellent job watching the system for problems, but as has been said before, there's so many things that can go wrong in the system that there will eventually be a failure.

Hey, that kinda sounds like the Convairliners. Then again, the hydraulic system in them is almost identical in form and function.

Have you guys tried Granville Strut Seal? It is made by Hydro-Chem engineering in Ft. Worth to help seal leaks in undercarriage struts, but is good for all 5606 type systems. In a small strut like a Spitfire you use only a few ounces, so a whole DC3 system might take a pint or two ? One cause of hydraulic leaks is seals and O rings become brittle and shrink. This treatment restores flexibility and full size. It works well, don't think there is any downside, and it is not expensive, and it seems to last at least a year or more. If it does not help then the problem may be one like a cracked fitting rather than a seal.

_________________
Bill Greenwood
Spitfire N308WK

Granville Strut Seal is really made for a short time fixs. We used it on the Kitty Hawk convairs to get birds back home that were leakers.. Sure it swells up the o rings for a while but your o rings are shot.

How much is the total hydraulic capacity of a DC-3? I assume there may be two separate systems, one for brakes and another for gear and flaps.

_________________
Bill Greenwood
Spitfire N308WK

It's 28 quarts - 13 in the reservoir and 15 in the lines and such.

Bill
The DC-3 hydraulic system is one system. engine driven pumps provide pressure with a cockpit backup hand pump. some planes had a electric back up to the backup installed. the system pressure (650-950 or there abouts) runs gear, flaps, cowl flaps, and wipers. the brakes are run off the same system, but have a Brake Booster device under the floorboards that amplifies system pressure to the brakes at the wheel. The wheels then had either expander tube ( ala cub) truck brakes ( ala every vehicle on the road) or multi puck type disk brakes. I have flown all 3 and much like a cub, you learn to not use the brakes as much as possible as they are weak at best and conveniently nonexistent when taxiing down hill with a full load of freight and a upcoming 90 left onto the runway
Simon

_________________
"Never in the field of human conflict was so much owed by so many to so few"