Transmission Fluid Sample Results

[ellisjte]

Hi all,

I bought a 97 Safari a few months ago and I'm going through all the things it needs.  One thing I wasn't sure of was the health of the transmission fluid.  According to some very detailed maintenance records that I received with the coach the Allison MD3060 was fully switched to Transynd at ~66,000 miles.  The coach now has a little over 102,000.  The mileage on the fluid isn't an issue, but the fluid is about 8 years old.  Fluid analysis looks good, nothing bad in it, and viscosity checks out at 7.1, new fluid rates at 7.4 I believe.  So I'm thinking all i need to do is a filter swap and top off the fluid with some more transynd.

I've attached a slightly redacted copy of my analysis and I'm hoping our friendly neighborhood retired Allison fluids engineer can pop in and validate or obliterate my conclusion.

 

Thanks!

Jason

[wildebill308]

Jason, While I am not a retired Allison fluids engineer nor have I played one on TV. I couldn't resist. I have in a past life run an oil analysis lab when in the AF. What one sample does is give you a snapshot of the condition of the fluid. It wouldn't hurt to change the filters and top off the fluid. I would sample again when you do your annual. What you want to look for is contamination and how much the wear metals go up between samples.

I have switched to Blackstone because they give universal averages for the level of wear metals for a component. This gives you a better handle on what you are seeing.

Bill

 

[ellisjte]

Thanks Bill.  I was Air Force too, SATCOM.  Not a lot of fluid in a milstar antenna though!

I figure the filters need to be changed on age alone since I can't find any mention of any maintenance on the tranny after the transynd switch over.  I'll get that done next week hopefully.

I figure on sampling again around December when the engine oil is due.

 

 

[dons2346]

Bill is correct. One sample isn't enough to give you any meaningful data. What you are looking for is a trend and look for any spikes in any data. This will take a number of samples to establish.

Back in my flying days, we ran 25 hour samples on the Mooneys. One particular aircraft was showing a rise in a particular metal but was in range but to be watched. The next sample said the plane should be grounded and do not fly it. To late because it was in a corn field. Good thing was, I wasn't flying it.

[manholt]

[hzjcm8]

Jason,

I was asked to comment on this.

Your Castrol TranSynd is still in good shape and doesn't need to be changed-- as evidenced by the report.    If the filters (main and lube) are around 8 years old, they may not be the newer "High Capacity" Allison filters.    So, I'd say drop the filters, change them out to the latest Allison "High Capacity" filters (see attachment), top off with TranSynd and resample to establish a new baseline. Sample on an annual basis and consider using the Ultimate Oil Analysis test kit that includes Particle Count and ISO Cleanliness Code.    The extra testing will provide a good assessment of the filtration system.    The Allison lube and main filters are rated at 50 microns so the Particle Count and ISO Cleanliness Code will tell us how the filters are performing.    I've attached the latest Allison "High Capacity" filter kit part numbers for your (and other forum members') use.

With respect to data limits not being shown on the report, we don't publish data limits (such as wear limits).   Limits can be confusing or "wearisome" to some folks.   Let's say you have a wear metal reading that's just borderline or just outside a published limit. So, what does that really mean?   As dons2346 said, it's more revealing to observe trends or data changes with respect to time (miles, hours, calendar time) and look for trend differences such as curve inflections, spikes, etc.    That's why we choose to use overall severity ratings:   "normal, abnormal and critical" ratings.   These "Severity Ratings" are established based on statistical distributions using hundreds of samples from similar equipment and similar fluids.   These population studies provide average and standard deviation data that enable us to place results into these severity ratings based on distance from the mean (standard deviation)..   So, although we don't publish limits, we do place a "Severity Rating" on the sample that can best be observed with respect to what the comments in the "Comments Section".   

Hope this helps !!    If not, send me a PM and I'll get back to you.

PS:    I am also former USAF (1968-1972).   I served at a now abandoned Nuclear Deterrent base along the North Sea during the Cold War.   I was a Weapons Specialist  (46250).   Upon getting my Honorable Discharge in 1972, I married, started a family and used my "GI Bill" to get a BSMET from Purdue University.    I also flew for a few years.   I was part of the Allison Engineering "Screaming Eagles" flying club.   We had (2) airplanes.   A Cessna 150 and a Cherokee 180.    Now I fly my desk using Microsoft Flight Simulator.   I can fly anywhere and not have to worry about malfunctions !!!

[ellisjte]

Very good info!  Thank you Tom.  I'm new to the oil analysis thing, I've always gone by the fluid or equipment manufacturer's recommendations for fluid changes.  I'll go ahead with the filter change and get a new baseline sample in.

[kaypsmith]

Tom, thanks for your service to our great country, and good choice in the flying career. As always very informative.