Oil Pressure Mushroom

H. Paul Shuch is a Light Sport Repairman with Maintenance ratings for airplanes, gliders, weight shift control, and powered parachutes, as well as an independent Rotax Maintenance Technician at the Heavy Maintenance level. He holds a PhD in Air Transportation Engineering from the University of California, and serves as Director of Maintenance for AvSport of Lock Haven.

Moderator: drseti

User avatar
FastEddieB
Posts: 2403
Joined: Wed Jan 07, 2009 9:33 pm
Location: Mineral Bluff, GA

Oil Pressure Mushroom

Postby FastEddieB » Thu May 03, 2018 7:28 pm

Quite some time ago I bought the new “mushroom” part that’s needed to go to a 2,000 hr TBO.

Image

What’s involved in installing it? Is it just a matter of pulling out the little ball and inserting the mushroom instead? I vaguely recall someone mentioning a different spring, but I only see one listed.

I did a quick search for the ROTAX SB concerning it with no luck.

Anyone?
Fast Eddie B.
Sky Arrow 600 E-LSA • N467SA
CFI, CFII, CFIME
FastEddieB@mac.com

3Dreaming
Posts: 2268
Joined: Sun Jan 10, 2010 6:13 pm
Location: noble, IL USA

Re: Oil Pressure Mushroom

Postby 3Dreaming » Thu May 03, 2018 8:42 pm

Actually it is not the mushroom that needs replaced to extend TBO. It is #3 and #5 the spring and cap. The mushroom can also be replaced if you have fluctuating oil pressure.

User avatar
drseti
Posts: 5671
Joined: Sat Nov 28, 2009 6:42 pm
Location: Lock Haven PA
Contact:

Re: Oil Pressure Mushroom

Postby drseti » Thu May 03, 2018 8:55 pm

You do need to replace both the pressure spring and the end cap with the new design. AFAIK, they no longer make the pre-2011 parts, so anything you buy from current inventory will satisfy the 2000 hour TBO requirement. Replacing the ball with the mushroom is not required (though some people have experienced oil pressure fluctuation, which the mushroom seems to cure). And, this mod only applies to the new crankcase design. Any crankcase s/n lower than 06.0010 is not eligible for the TBO extension.

Eddie, when you open up the pressure relief valve assembly, be sure to perform an oil system pressure purge before starting the engine. There is a Service Instruction for that on rotax-owner.com.
The opinions posted are those of one CFI, and do not necessarily represent the FAA or its lawyers.
Prof H Paul Shuch
PhD CFII DPE LSRM-A/GL/WS/PPC iRMT
AvSport LLC, KLHV
fly@AvSport.org
AvSport.org
facebook.com/SportFlying
SportPilotExaminer.US

User avatar
FastEddieB
Posts: 2403
Joined: Wed Jan 07, 2009 9:33 pm
Location: Mineral Bluff, GA

Re: Oil Pressure Mushroom

Postby FastEddieB » Fri May 04, 2018 6:31 am

Thanks to you both. I thought it was just the mushroom that needed replacing.

1) I’m about to have the 5-year rubber parts replacement done. Seemed like a good time to make the swap. The system obviously needs purging at that time regardless.

2) Or, with no oil pressure fluctuation problems in 11 years, I could just leave well enough alone and save at least $50 in additional parts. Doing the math, if I keep flying at roughly the same rate - 500+ hours in 11 years - I’ll be 90 (!) by the time I hit 1,500 hrs and it becomes an issue. If I’m even still flying then - I hope so - I can worry about it then.

But, “wisdom of the crowd” and all that, what would you do?
Fast Eddie B.
Sky Arrow 600 E-LSA • N467SA
CFI, CFII, CFIME
FastEddieB@mac.com

User avatar
drseti
Posts: 5671
Joined: Sat Nov 28, 2009 6:42 pm
Location: Lock Haven PA
Contact:

Re: Oil Pressure Mushroom

Postby drseti » Fri May 04, 2018 7:39 am

FastEddieB wrote:
if I keep flying at roughly the same rate - 500+ hours in 11 years - I’ll be 90 (!) by the time I hit 1,500 hrs and it becomes an issue.


From this, I infer yours is a 2007 engine. Thus, we've established that it's apparentry eligible for the upgrade (by crankcase s/n). So...

Rotax TBO involves two numbers, Hobbs (not tach!) hours and time in service. The latter is often overlooked. I believe yours is 12 years (you'll have to check the engine s/n against the list in the Service Bulletin to be sure). If so, you're now 1 year away from TBO, regardless of hours flown. Compliance with the SB brings your TBO up to 15 years (buying you only an extra 3).

Now, before you panic, TBO is not regulatory, merely advisory. And since yours is an Experimental, you can probably be justified (and safe) in ignoring the 12 year limit. So, if you choose to stop reading here, nobody's going to blame you.

Still with me? Then consider that I'm in a different situation. As a commercial operator, I'm subject to both scrutiny and legal liability. For me, the calendar limit is potentially serious. This is one of the reasons flight schools tend to turn over their fleets with some degree of regularity.

All of this was covered in my recent EAA Webinar "What TBO Really Means." For those who missed it, here's the link:

http://www.eaavideo.org/detail/video/5752102647001
The opinions posted are those of one CFI, and do not necessarily represent the FAA or its lawyers.
Prof H Paul Shuch
PhD CFII DPE LSRM-A/GL/WS/PPC iRMT
AvSport LLC, KLHV
fly@AvSport.org
AvSport.org
facebook.com/SportFlying
SportPilotExaminer.US

User avatar
ShawnM
Posts: 214
Joined: Sat Nov 11, 2017 9:59 pm
Location: Clearwater, FL

Re: Oil Pressure Mushroom

Postby ShawnM » Fri May 04, 2018 7:46 am

Thanks for the explanation Paul.

When I did mine Lockwood had a "kit" for about $60 I think. I didn't have any oil pressure issues but wanted the extra TBO tacked on. Mine is also a 2007 engine. I figure it cost me about $0.12 for each hour added. :mrgreen:

roger lee
Posts: 729
Joined: Tue Dec 08, 2009 11:47 am
Location: Tucson, Az. Ryan Airfield (KRYN)

Re: Oil Pressure Mushroom

Postby roger lee » Fri May 04, 2018 8:18 am

"Now, before you panic, TBO is not regulatory, merely advisory."

This is back in FAA legal as we speak and has been for 4 months. I still may take 1.5 years for them to render a decision. This has been in legal twice now. This could stay on condition or it could change. Time will tell. This hinges on 1-2 words.

Rotax "Service Bulletins" that are labeled mandatory are also fast tracking through the system and these may be mandatory soon. These may be mandatory soon. This will be their 2-3 time through legal.
Roger Lee
Tucson, Az.
LSRM-A, Rotax Instructor & Rotax IRC
(520) 574-1080 (Home) Try Home First.
(520) 349-7056 (Cell)

User avatar
drseti
Posts: 5671
Joined: Sat Nov 28, 2009 6:42 pm
Location: Lock Haven PA
Contact:

Re: Oil Pressure Mushroom

Postby drseti » Fri May 04, 2018 8:30 am

roger lee wrote:Rotax "Service Bulletins" that are labeled mandatory are also fast tracking through the system and these may be mandatory soon.


I don't understand why FAA Legal has to be involved in this one. If Rotax wants to force compliance, under present rules all they have to do is issue them as Safety Bulletins rather than Mandatory Service Bulletins. Those already have the same force of law as ADs.
The opinions posted are those of one CFI, and do not necessarily represent the FAA or its lawyers.
Prof H Paul Shuch
PhD CFII DPE LSRM-A/GL/WS/PPC iRMT
AvSport LLC, KLHV
fly@AvSport.org
AvSport.org
facebook.com/SportFlying
SportPilotExaminer.US

3Dreaming
Posts: 2268
Joined: Sun Jan 10, 2010 6:13 pm
Location: noble, IL USA

Re: Oil Pressure Mushroom

Postby 3Dreaming » Fri May 04, 2018 9:10 am

drseti wrote:
roger lee wrote:Rotax "Service Bulletins" that are labeled mandatory are also fast tracking through the system and these may be mandatory soon.


I don't understand why FAA Legal has to be involved in this one. If Rotax wants to force compliance, under present rules all they have to do is issue them as Safety Bulletins rather than Mandatory Service Bulletins. Those already have the same force of law as ADs.


Rotax can't force compliance. That would have to come from an airworthiness directive or safety directive from the aircraft manufacturer.

User avatar
MrMorden
Posts: 1894
Joined: Fri Aug 17, 2012 7:28 am
Location: Athens, GA

Re: Oil Pressure Mushroom

Postby MrMorden » Fri May 04, 2018 9:18 am

3Dreaming wrote:
Rotax can't force compliance. That would have to come from an airworthiness directive or safety directive from the aircraft manufacturer.


That's my understanding as well. The engine is just like any other component or part; the component manufacturer can make recommendations, but only the *aircraft* manufacturer can make it regulatory by issuing a SB or AD.
Andy Walker
Athens, GA
Sport Pilot ASEL, LSRI
2007 Flight Design CTSW E-LSA

User avatar
FastEddieB
Posts: 2403
Joined: Wed Jan 07, 2009 9:33 pm
Location: Mineral Bluff, GA

Re: Oil Pressure Mushroom

Postby FastEddieB » Fri May 04, 2018 10:38 am

Thanks for all the input.

I think this shows the limitations of attempting to follow the “Most Conservative Action” rule.

On the one hand, The Most Conservative Action in my case is obviously to do nothing, along the lines of “If it ain’t broke...” or “Leave well enough alone”. Messing with it just provides an opportunity for a Maintenance Induced Failure, with no perceived immediate benefit.

On the other hand, The Most Conservative Action in my case is obviously to follow the manufacturer’s recommendation, and to makes sure my engine has the most up-to-date parts, which they hold to be an improvement over the ones currently installed.

I think my tendency to fall back on the first option was brought up in my recent fuel pump thread, where we learned the term “Status Quo Bias”.

I’ll probably go ahead with the second option, when the system is opened up anyway for the oil line change. That way I won’t have to worry about it when I’m 90(!).

To be clear, I would also need to order the spring and “plug screw”, items #3 and #5 respectively in the above diagram, right? What about the shim, #4?
Fast Eddie B.
Sky Arrow 600 E-LSA • N467SA
CFI, CFII, CFIME
FastEddieB@mac.com

User avatar
MrMorden
Posts: 1894
Joined: Fri Aug 17, 2012 7:28 am
Location: Athens, GA

Re: Oil Pressure Mushroom

Postby MrMorden » Fri May 04, 2018 10:50 am

FastEddieB wrote:Thanks for all the input.

I think this shows the limitations of attempting to follow the “Most Conservative Action” rule.

On the one hand, The Most Conservative Action in my case is obviously to do nothing, along the lines of “If it ain’t broke...” or “Leave well enough alone”. Messing with it just provides an opportunity for a Maintenance Induced Failure, with no perceived immediate benefit.

On the other hand, The Most Conservative Action in my case is obviously to follow the manufacturer’s recommendation, and to makes sure my engine has the most up-to-date parts, which they hold to be an improvement over the ones currently installed.

I think my tendency to fall back on the first option was brought up in my recent fuel pump thread, where we learned the term “Status Quo Bias”.

I’ll probably go ahead with the second option, when the system is opened up anyway for the oil line change. That way I won’t have to worry about it when I’m 90(!).

To be clear, I would also need to order the spring and “plug screw”, items #3 and #5 respectively in the above diagram, right? What about the shim, #4?


When I did mine, Roger Lee told me the shim was rarely needed unless there is a problem. IIRC I ordered the three parts needed as a kit, but I might be misremembering and have ordered them separately.
Andy Walker
Athens, GA
Sport Pilot ASEL, LSRI
2007 Flight Design CTSW E-LSA

3Dreaming
Posts: 2268
Joined: Sun Jan 10, 2010 6:13 pm
Location: noble, IL USA

Re: Oil Pressure Mushroom

Postby 3Dreaming » Fri May 04, 2018 11:50 am

I would not consider installing the shim, unless I had low oil pressure verified independently by a mechanical gauge.

User avatar
drseti
Posts: 5671
Joined: Sat Nov 28, 2009 6:42 pm
Location: Lock Haven PA
Contact:

Re: Oil Pressure Mushroom

Postby drseti » Fri May 04, 2018 12:04 pm

The shims are used to adjust oil pressure to the desired value. I always keep a few in stock. They're seldom required, but occasionally an oil pressure regulator may require 1, 2, or (seldom) even 3 to meet target pressure.
The opinions posted are those of one CFI, and do not necessarily represent the FAA or its lawyers.
Prof H Paul Shuch
PhD CFII DPE LSRM-A/GL/WS/PPC iRMT
AvSport LLC, KLHV
fly@AvSport.org
AvSport.org
facebook.com/SportFlying
SportPilotExaminer.US

User avatar
FastEddieB
Posts: 2403
Joined: Wed Jan 07, 2009 9:33 pm
Location: Mineral Bluff, GA

Re: Oil Pressure Mushroom

Postby FastEddieB » Fri May 04, 2018 12:22 pm

I'm probably going to order the parts this afternoon.

First, I want to check my logbook to be sure Roger didn't maybe do it at the last hose change.
Fast Eddie B.
Sky Arrow 600 E-LSA • N467SA
CFI, CFII, CFIME
FastEddieB@mac.com


Return to “Ask The Mechanic”

Who is online

Users browsing this forum: No registered users and 1 guest