MAP/Fuel Pressure Gauge equivalency

[FlyingDude]

Hi all,

Is a 660063-3 MAP/FP gauge (pn 22-469-01A, unknown manufacturer) on an 1967 E equivalent to a 660063-501 or -503 on a 1968 onwards E or F (pn 21M102 by Aircraft Instruments and Development Inc, of Wichita, KS) ? 

[edit, 4 days later, to save anyone looking for this info, time]. YES, they are.  Called Lasar on Feb 16, 2021 and -3 has been superseded by -503 and -503 and -501 are interchangeable.

All these gauges have the same pressure ranges and I think all these aircraft are fitted with Lycoming IO360-A1A. Would that mean that they all have the same manifold and injector structures?  I saw that they have different codes for the restrictors and hoses, though.  Anyway, I need to do my homework and convince my mechanic that they are pretty much the same thing...  And also, (God forbid) if an accident happens, I wouldn't want insurance to grip on to a discrepancy in instrumentation (since MAP / Fuel pressure are among required instruments)…  A few guys here helped me A LOT, but we couldn't find any conclusive evidence...  

What info can I gather to make my case?  What info should be entered into the logs?

Thanks a lot!

F

Edited February 16, 2021 by FlyingDude

[PT20J]

I’d call LASAR. They’ve looked up parts for me to get info on equivalents. Or email tech support at Mooney.

Skip

[75_M20F]

Well my fuel pressure / MP gauge was stuck on 5PSI no matter what. I removed it and sent it off for repair. Cost me $200 and it is back in service.

My 75F has the 66003-503 version. It requires an inline restrictor on the MP line under the cowling.

There is a small amount of information in the Mooney parts manual if you can decipher it.

 

 

Edited February 13, 2021 by 75_M20F

[carusoam]

Wait a minute....

Lets not condemn the gauge just yet...

The line from the engine to the gauge is connected to a hazardous environment on one end....

...And a pretty clean and nice environment on the other end...

On the engine end... it is connected to a place where fuel and air can be mixed...

Each time the engine is shut down, the air/fuel mixture can be brought towards the gauge...

There is one thing that keeps that mess from making it to the gauge...

The calibrated leak hole...

The calibrated hole is tiny, and open to the atmosphere...

it is located within an inch or two of the gauge itself...

The good news... the line probably needs a good cleaning...

At the cylinder... the line is a small diameter piece of copper....

on the inside of the firewall... the copper line ends and an aluminum line is used...

It’s quite possible, your mechanic can have this cleaned out and working normally in a very short period of time...

It is a challenge for me to say how much blue goo can make it that far in an M20F that has fuel injection...

But, in an M20C where the fuel is mixed with air before the intake tubes... all the blue colorant falls out of solution with evaporation.... the intake tubes are coated with blue goo....

The reason for the calibrated leak... it bleeds air back into the system... so when you shut down the engine.... the fuel air mixture isn’t sucked all the way to the gauge...

Chances are... a fair amount of mess has grown at the engine end of the line...

If you are seeing delays in the change of the MP needle... expect something is slowing the air from equilibrating... in the gauge...

More good news... the plumbing in older Mooneys is off the shelf copper and aluminum tubing....

Inspect the health of the calibrated hole while you are in there... it has the tendency to vibrate and can produce a crack that propagates until the calibrated hole is no longer calibrated... or a hole...

 

PP thoughts only, not a mechanic...

Best regards,

 

-a-

[FlyingDude]

1 hour ago, PT20J said:

I’d call LASAR. They’ve looked up parts for me to get info on equivalents. Or email tech support at Mooney.

Skip

Yeah, I sent Mooney an email inquiring about the equivalency. I'll post their answer here. Thanks.

[FlyingDude]

42 minutes ago, carusoam said:

Wait a minute....

Lets not condemn the gauge just yet...

The line from the engine to the gauge is connected to a hazardous environment on one end....

...And a pretty clean and nice environment on the other end...

On the engine end... it is connected to a place where fuel and air can be mixed...

Each time the engine is shut down, the air/fuel mixture can be brought towards the gauge...

There is one thing that keeps that mess from making it to the gauge...

The calibrated leak hole...

The calibrated hole is tiny, and open to the atmosphere...

it is located within an inch or two of the gauge itself...

The good news... the line probably needs a good cleaning...

At the cylinder... the line is a small diameter piece of copper....

on the inside of the firewall... the copper line ends and an aluminum line is used...

It’s quite possible, your mechanic can have this cleaned out and working normally in a very short period of time...

It is a challenge for me to say how much blue goo can make it that far in an M20F that has fuel injection...

But, in an M20C where the fuel is mixed with air before the intake tubes... all the blue colorant falls out of solution with evaporation.... the intake tubes are coated with blue goo....

The reason for the calibrated leak... it bleeds air back into the system... so when you shut down the engine.... the fuel air mixture isn’t sucked all the way to the gauge...

Chances are... a fair amount of mess has grown at the engine end of the line...

If you are seeing delays in the change of the MP needle... expect something is slowing the air from equilibrating... in the gauge...

More good news... the plumbing in older Mooneys is off the shelf copper and aluminum tubing....

Inspect the health of the calibrated hole while you are in there... it has the tendency to vibrate and can produce a crack that propagates until the calibrated hole is no longer calibrated... or a hole...

 

PP thoughts only, not a mechanic...

Best regards,

 

-a-

So the diameter of the orifice wouldn't affect the pressure felt on the other side, it only restricts air flow to slow down pressure equalization. I think they put that in place such that the oscillations on the manifold as valves open and close don't translate into shaking needles in the gauge. 

I'll definitely clean the line tomorrow. Hopefully it's just goo...

Thanks a lot!

[carusoam]

There are two types of holes used with our pressure gauges....

1) FP... has the internal hole to minimize needle fluctuation... that is called a snubber.  the internal hole works really well as a damper... as long as air is the only thing traversing through the hole... an external hole would be bad for liquids.... 

2) The MP... has an external hole that is to keep the gauge clean... an internal hole wouldn’t keep the gauge clean...

PP thoughts only, not a mechanic...

Best regards,

-a-

[FlyingDude]

It's -8C out here in SE MI and snowing... Unheated hangar. For now, I'd rather stay home and obsess about it until a "warmer" day

Or read, with the kids playing next to me...

F

Edited February 13, 2021 by FlyingDude

[FlyingDude]

It warmed to -3C here, so I headed to the hangar. Special applause to @carusoamfor not losing faith in the gauge or at least emphasizing the culpability of the line. I disconnected it from both on the gauge and the engine side, and blew air into it with compressor. Reconnected it on the gauge side and sucked on it from the engine side: comes down to 25" and goes back to 30" (today H here) without getting stuck. Didn't remove the restrictor from the engine because there was some teflon on it, which I didn't have with me. Blew some air into the restrictor only.

Didn't do a running check with engine on, hopefully will go fly tomorrow or Monday. Hopefully nothing goes wrong.

Now, weirdnesses: the parts manual lists hoses and restrictors on the injector. In my case, there's only a restrictor screwed into the cylinder head on Cyl 3.  The entire hose is really skinny, like 3mm (1/8") at most firewall forward, and 1mm metal tube aft of firewall... Injector only has fuel feed and fuel pressure hose...

[PT20J]

Teflon tape is not the best choice for a sealant for tapered pipe thread fittings. Bits can get loose and clog things. 

Skip

[FlyingDude]

Exactly. They're specifically prohibited on vacuum lines. I don't know why there's some on this. I'll check that with my mechanic and potentially remove any teflon. I don't want to take this initiative without his blessing first. Who knows, maybe it was teflon that clogged the line in the first place!

Edited February 14, 2021 by FlyingDude

[carusoam]

That would be a typical Teflon tape type of failure... a small shred braking free, then finding a tiny hole to stick in...

There are very few places that Teflon tape gets properly used in a Mooney...

Use extra caution to make sure no excess tape is allowed to be in the interior of the tube...

 

Typical home use, excess Teflon tape is stretched over the end of the threads, with no regard to where the extra bits can go...

PP thoughts only, not a mechanic or a plumber...

Best regards,

-a-

[FlyingDude]

I agree, it makes sense.

I'm going to ask my mechanic if I can just screw the restrictor in without anything. After all, vacuum lines are all dryfit...

[FlyingDude]

On 2/13/2021 at 9:02 PM, carusoam said:

There are very few places that Teflon tape gets properly used in a Mooney

In what other parts of the plane is teflon used? Is it the same teflon that you use at home plumbing?? I looked on spruce, but couldn't find any...

Thanks.

[carusoam]

 

Dude,

From @M20Doc himself...  
 

I thought I was going to be challenged looking this one up...   

Doc is an MSC level mechanic... he really knows his details...

The quote box isn’t doing a great job of showing who said what here...

This is the part that came from Doc... (aka Clarence)

  “I was taught that Teflon tape has no place in aircraft other than in oxygen systems where oil based sealants can cause explosion or fire. Mooney says to use Parker Thread lube for fuel, hydraulic, oil and air fitti....”

Got any more really tough questions...?  

Best regards,

-a-

[FlyingDude]

Hey A,

Thanks

Well, I trusted your knowledge, that's why I asked. I couldn't find the Parker lube on spruce. Is this also good?

PERMATEX THREAD SEALANT 1.69OZ 56521

Part #: 15-06149

thanks again

F

[David Lloyd]

One problem always with thread sealant: Unlike money, too much is a bad thing, It goes places not intended. That's why it gets a bad reputation.  Read the directions on how much and where.

One problem always with teflon tape: Unlike money, too much is a bad thing, it goes places not intended.  That's why it gets a bad reputation.  Read the directions on how much and where.  I once watched an A&P/IA wrap tape on an NPT fitting in the wrong direction.

[N201MKTurbo]

I was working on a high pressure system once. It had beautiful Swagelok fittings. One was a pipe thread. I assembled it with no sealant and it leaked with 3000 PSI. I put it together with the specified two turns of mil spec Teflon tape. It didn't leak. I took it apart, cleaned all the tape off and cut a tiny little strip of tape, it barely covered one thread. I wrapped around so it barely overlapped, about 1.2 turns. It didn't leak with 3000 PSI (checking it with Snoop). 

The point is it takes very little Teflon tape to do its job. Most people put on WAY too much.

MIL SPEC T-27730A

[FlyingDude]

3 hours ago, David Lloyd said:

I once watched an A&P/IA wrap tape on an NPT fitting in the wrong direction

Ouch!!!

I'm not sure about money though. A college buddy of mine inherited 3+ million euro worth of real estate. Residential, commercial and land... The paranoia of thinking everyone is out there to take his money away ruined his life... It's like fuel. You never have too much, unless you're on fire...

Edited February 15, 2021 by FlyingDude

[Tcraft938]

On 2/12/2021 at 8:00 PM, 75_M20F said:

Well my fuel pressure / MP gauge was stuck on 5PSI no matter what. I removed it and sent it off for repair. Cost me $200 and it is back in service.

My 75F has the 66003-503 version. It requires an inline restrictor on the MP line under the cowling.

There is a small amount of information in the Mooney parts manual if you can decipher it.

 

 

Who did your MP gauge overhaul work?  I need to do mine.  Thanks. 

[David Lloyd]

Another thread shows Rudy Instruments listing a FP/MP gauge overhaul at $175.  http://rudyaircraftinstruments.com/

[75_M20F]

7 hours ago, Tcraft938 said:

Who did your MP gauge overhaul work?  I need to do mine.  Thanks. 

I was not pleased with the place that overhauled my FP/MP gauge. First they were really slow, then once I got it back it was not working properly so I had to send it back to them again....  So I can't recommend them.

[FlyingDude]

Guys,

Good news.  Just talked to Chad at Lasar and he confirmed that their system shows that 660063-3 has been superseded by 660063-503 and that -503 and -501 are interchangeable.  Phew...

 

Edited February 16, 2021 by FlyingDude

[RobertGary1]

5 hours ago, FlyingDude said:

Guys,

Good news.  Just talked to Chad at Lasar and he confirmed that their system shows that 660063-3 has been superseded by 660063-503 and that -503 and -501 are interchangeable.  Phew...

 

So can they overhaul it for you?

 

-Robert

[FlyingDude]

17 hours ago, RobertGary1 said:

So can they overhaul it for you?

 

-Robert

Didn't ask that. Don't know

I'm in MI, they're in CA. There are avionics shops within 20 mile radius... So I didn't ask...

 

Edited February 17, 2021 by FlyingDude