Hydraulic fluid

[mjoekingz28]

Hello, my dad inspects hydraulic parts for aircraft and some use skydroil.


Is there any information you can give me on fluid changes for aircraft?



I asked him today to help me bleed the brakes in my 12 year old truck and he asked if it was because of a problem. I said no, just wanted fresh fluid in there because the old fluid had what looked like rubber particles and looked as dark as burnt motor oil.

Ayways, im trying to convince hime that there is more to maintaining a car besides changing the motor oil. Especially since his truck has 210k, the most ever by him, and he wants to keep the truck til its too expensive to do so. Thanks.

 

[tom slick]

Here's some
http://www.faa.gov/regulations_policies/...ia/ama_ch12.pdf

 

[JHZR2]

Not sure what the one half has to do with the other...

 

[stranger706]

Originally Posted By: mjoekingz28
Hello, my dad inspects hydraulic parts for aircraft and some use skydroil.

Is there any information you can give me on fluid changes for aircraft?


Well generally in large aircraft you do not change the fluid very often like in a car. It actually stays really clean. There are filters and sensors everywhere so if the slightest problem came up there would be an indication on the flightdeck immediately. But thats pretty rare. Also maintenance will take samples and send those in to get analyzed on a regular basis. Just like a UOA here.

The system reserviors will get topped up from time to time and components ops checked on a regular basis. But to actually drain the fluid to change it is very rare. Because you never want to introduce air into the system as it is very hard to get out. You don't want an air pocket in your hydraulic system while you are flying.

 

[DrDave]

Inspection at annual does not include flushing hydraulic systems or brake systems. Some planes like the early 210's had hydraulic flaps and landing gear. There is only a screen on the hydraulic unit. I think a UOA with particle count could convince an interested person to flush the fluid. Most of those used 5606.

At the time the service manuals were written there was no consideration for UOA.

Dave

 

[Cujet]

I operate 5 different aircraft. Our Gulfstream G550 has 2 Rolls Royce BMW engines. Each engine drives an independent hydraulic system. The engines use Exxon/BP 2380 oil, a thin ester synthetic oil. The engines do not get oil changes, however, they do get oil filter changes. No oil analysis either.

The hyd systems each use Skydrol LD-4 synthetic hyd fluid. We regularly hook the aircraft up to a hydraulic mule (an external hyd pump) to test the systems. Because we cannot risk aircraft and mule contamination, the hyd fluids in the LH and RH and mule systems are carefully tested prior and after mule use. At 5PPM, the fluid gets changed and flushed carefully. The aircraft is extremely sensitive to contamination. (the hyd pump is behind my head and you can't see it)

Our Pilatus PC-12 has a Pratt PT-6 turboprop and also uses 2380 oil. It gets yearly oil changes and oil analysis. It has a single electrically driven hyd system and uses 5606 (red, mineral based) hyd fluid. We do not change the fluid, or ever service it, unless something goes wrong.

Our Eurocopter EC-135 has 2 Turbomeca engines that use 2380 and get yearly changes, without analysis. Both hyd systems use 5606 and get yearly fluid changes without analysis.

 

[ironman_gq]

Originally Posted By: mjoekingz28
Hello, my dad inspects hydraulic parts for aircraft and some use skydroil.


Is there any information you can give me on fluid changes for aircraft?



I asked him today to help me bleed the brakes in my 12 year old truck and he asked if it was because of a problem. I said no, just wanted fresh fluid in there because the old fluid had what looked like rubber particles and looked as dark as burnt motor oil.

Ayways, im trying to convince hime that there is more to maintaining a car besides changing the motor oil. Especially since his truck has 210k, the most ever by him, and he wants to keep the truck til its too expensive to do so. Thanks.


Explain to him how brake fluid is hydroscopic and the system is not truly sealed and it absorbs moisture from the air which leads to a lower boiling point of the fluid and potential safety hazard.