Departure Emergency - Challenger Oil Filter

[alextstone]

As you are aware, parts availability has been an issue lately.  With that in mind, I decided to install a Challenger reusable oil filter on my 1995 Bravo.  Actually, an A&P who works at my shop did it for me.  I flew the airplane about an hour last weekend with no issues.  This morning, as I departed my home field climbing through about 600 ft AGL, my manifold pressure dropped from 36" to 32".  I immediately looked over my left shoulder and started a turn back to the field. When I looked back at the MP, it had dropped to 25" and was continuing to fall.  I declared an emergency and landed.  The engine ran smoothly the entire time.  As I was rolling to the taxiway, I noted that the oil pressure had dropped to zero.  I shut the engine down and I was towed back to the shop....

 

 

 

 

 

 

In that span of time, I lost virtually all of the engine oil.  The instructions for installation of the filter state that one should spin it on until resistance is felt and then turn 1/4 turn, which the A&P was confident he did.  As you can see from the photos, the seal seems to be slightly larger in diameter than the slot that is machined into the filter that houses it.  

 

What is your opinion?  Is the seal a poor design, are the instructions incorrect (more tightening required)?  Was the filter simply installed incorrectly? A combination?

Does this rise to the level of an FAA service difficulty report?

 

Thanks for your input.

 

Alex Touchstone

 

[EricJ]

Looks like an installation error to me.   An unfortunate one, no doubt, but nevertheless.

 

[Mooney in Oz]

I’ll let others chime in with their opinions as to the cause of what could’ve been a tragic outcome.

Well done in keeping your cool and bringing you and your bird in to land safely resulting in a good outcome. I’m also glad this didn’t occur during an IMC or night departure. 

[carusoam]

Nice catch!
 

The o-ring appears to have swollen, as if it has absorbed the oil….

The Wrong material O-rings tend to absorb fuel or oil, and grow in size…

It is too big to fit in the space provided, so it can’t seal the way it was designed….

As far as torque specs… that works on my Chevy…

Let’s invite @M20Doc to the conversation…

Best regards,

-a-

[alextstone]

18 minutes ago, carusoam said:

Nice catch!
 

The o-ring appears to have swollen, as if it has absorbed the oil….

The Wrong material O-rings tend to absorb fuel or oil, and grow in size…

It is too big to fit in the space provided, so it can’t seal the way it was designed….

As far as torque specs… that works on my Chevy…

Let’s invite @M20Doc to the conversation…

Best regards,

-a-

I have an extra seal that came with the filter.  I placed it on the filter and it it also slightly larger in diameter, FWIW

[alextstone]

22 minutes ago, Mooney in Oz said:

I’ll let others chime in with their opinions as to the cause of what could’ve been a tragic outcome.

Well done in keeping your cool and bringing you and your bird in to land safely resulting in a good outcome. I’m also glad this didn’t occur during an IMC or night departure. 

I've been refecting on that very thing... Would I have been able to navigate back in IMC?  I practice that scenario and I never want to try it for real

[carusoam]

13 minutes ago, alextstone said:

I've been refecting on that very thing... Would I have been able to navigate back in IMC?  I practice that scenario and I never want to try it for real

this situation is what makes departing, single engine, into low IFR a real statistical challenge….

Plan A, is still land straight ahead…

Plan B, probably depends on how well you know the surrounding area…. Open fields, or tall buildings and antennas…..

 

With the two o-rings…. If you can…. Check to see if they are the same diameter…. Contact the people that supplied them…. Show them your pictures… I bet they would want to see that….

 

If I see the picture correctly… the seal escaped during installation…

O-ring selection… usually has the o-ring tighter than what is shown here…

When the o-ring gets slightly out of the channel it can get caught and twist as the mating surfaces go past each other…

(Check if the install instructions include lubing the o-ring or dry ‘torque’….)

 

Let’s see if @Hank is around… (engineering question and o-rings)

Best regards,

-a-

[Guest]

We’ve installed a few of these filters, one on our RV7.  It has 20 plus hours so far with no issues so far.  I’ll have to look at the spare seal that came with it.

I have another set on a C340 with more hours and no issues so far.

 

[jetdriven]

I'd definately SDR that.  Theres a lot of parts substitution for inferior goods going on, that could be a non-conforming o-ring that swells when it hits oil.

[kortopates]

IMO, i’d blame it on the O-ring; especially seeing another new one doesn’t fit either and thus the original one wasn’t just deformed by the installation. i am betting it got pinched outside of the groove as it was spun on. Then tightening it probably would only serve to deform the O-ring further.
I am just surprised it didn’t leak to some degree during the leak check. I guess it didn’t get enough oil pressure till departure.
i would write a SDR but only after talking to the OEM first to see to what they have to say.


Sent from my iPhone using Tapatalk

[Hank]

48 minutes ago, carusoam said:

this situation is what makes departing, single engine, into low IFR a real statistical challenge….

Plan A, is still land straight ahead…

Plan B, probably depends on how well you know the surrounding area…. Open fields, or tall buildings and antennas…..

 

With the two o-rings…. If you can…. Check to see if they are the same diameter…. Contact the people that supplied them…. Show them your pictures… I bet they would want to see that….

 

If I see the picture correctly… the seal escaped during installation…

O-ring selection… usually has the o-ring tighter than what is shown here…

When the o-ring gets slightly out of the channel it can get caught and twist as the mating surfaces go past each other…

(Check if the install instructions include lubing the o-ring or dry ‘torque’….)

 

Let’s see if @Hank is around… (engineering question and o-rings)

Best regards,

-a-

I use lots of O-rings all the time, but mostly the round ones; flat ones like this are a little different. Regardless of shape, a large O-ring will fit poorly or not at all into its channel, and whatever it is supposed to seal on will get out.

My oil filters on my cars I've always lubed with engine oil, spin til they touch, then another 3/4 turn; they go on by hand, but need help coming off.

On my Mooney, I also lube with engine oil, spin til they touch then spin turns by the instructions (reread to confirm how many turns, the airplane engine is a little more important, and expensive!). 

But if I read the OP's posts correctly, the large O-ring wasn't caused by exposure to / absorption of engine oil, because the unused spare O-ring was also too large. To me, either the O-ring was cut too large ir the wrong ones were packaged with the filter.

How is your engine now? Running even low power for a couple of minutes as your remaining oil was ejected is a frightening thought to me . . . . .

[GeeBee]

Nice job. getting back to the field.

It is not an O-ring but a "Quad Seal". It is supposed to be resistant to rolling forces on installation that often cause misalignment with o-ring designs. I run into these on diesel fuel filter where there is also significant pressure. A good quad ring should fit tightly around the inside diameter such that you can pick the unit up and not be able to shake the ring loose. That said, there are ways for it to go wrong

1. Uneven lubrication of the ring. This can cause it to "snag" during tightening. The only reliable way is to "soak it" in a tray of fluid to insure it is completed lubed.

2. Defect on either the adapter surface or the filter quad ring channel which will snag the seal. I would check your adapter surface.

 

That all said one thing that disturbed me about the Challenger filter (and leaves them an out and dissuaded me) is in the IFCA it says:

5. Check oil filter and pressure every pre-flight inspection.

[alextstone]

7 hours ago, M20Doc said:

We’ve installed a few of these filters, one on our RV7.  It has 20 plus hours so far with no issues so far.  I’ll have to look at the spare seal that came with it.

I have another set on a C340 with more hours and no issues so far.

 

Thanks, I am interested in how yours compares...

[ArtVandelay]

1/4 turn? Define resistance. If they mean hand tighten and then tighten an extra 1/4 turn using a wrench, then okay.
But if they mean any resistance felt, then no way..

[Fly Boomer]

3 hours ago, ArtVandelay said:

1/4 turn? Define resistance. If they mean hand tighten and then tighten an extra 1/4 turn using a wrench, then okay.
But if they mean any resistance felt, then no way..

They may know that over-tightening will deform the “o-ring”.  I have a lot more experience with car filters, but tightening with a wrench was neither desirable or necessary.

[1980Mooney]

16 hours ago, alextstone said:

As you are aware, parts availability has been an issue lately.  With that in mind, I decided to install a Challenger reusable oil filter on my 1995 Bravo.  Actually, an A&P who works at my shop did it for me.  I flew the airplane about an hour last weekend with no issues.  This morning, as I departed my home field climbing through about 600 ft AGL, my manifold pressure dropped from 36" to 32".  I immediately looked over my left shoulder and started a turn back to the field. When I looked back at the MP, it had dropped to 25" and was continuing to fall.  I declared an emergency and landed.  The engine ran smoothly the entire time.  As I was rolling to the taxiway, I noted that the oil pressure had dropped to zero.  I shut the engine down and I was towed back to the shop....

 

 

 

In that span of time, I lost virtually all of the engine oil.  The instructions for installation of the filter state that one should spin it on until resistance is felt and then turn 1/4 turn, which the A&P was confident he did.  As you can see from the photos, the seal seems to be slightly larger in diameter than the slot that is machined into the filter that houses it.  

What is your opinion?  Is the seal a poor design, are the instructions incorrect (more tightening required)?  Was the filter simply installed incorrectly? A combination?

Does this rise to the level of an FAA service difficulty report?

Thanks for your input.

Alex Touchstone

You note "I lost virtually all of the engine oil." -  How much oil was remaining when you drained whatever was left? 

You also said " As I was rolling to the taxiway, I noted that the oil pressure had dropped to zero."  Since you were focused on flairing and landing during final you probably don't know exactly when all oil pressure was lost to zero.  Perhaps you have an engine monitor that records it.

Residual oil film clinging to surfaces can provide a level of lubrication but I would be concerned about connecting rod bearings and the main bearings.  The connecting rod bearings are downstream of the main bearings in the oil flow path and they generally go first during oil starvation.  As Mike Busch pointes out when you lose hydrodynamic lubrication (with zero oil pressure like you experienced) you get metal to metal contact.  You may have little wear and damage or you may have considerable depending on how long, engine speed and load (i.e. temperature and bearing pressures as well as bearing condition at time - "smoothness")

Also you mentioned that you experience a loss in MP with no change in engine control.  Would that be caused by the turbo.?  The attached article by Aviation Safety says that turbo systems are designed with a pressure check valve that closes upon loss of oil pressure thereby trapping some oil in the turbocharger bearings and avoiding rapid disintegration while at 20,000 - 80,000 RPM.

"Hot side failures in turbine wheels-again, theyre rare-are likely to take the shaft and bearings out, meaning the engine will puke much of its oil but should retain enough to run for quite some time. Thats because turbocharger oil systems are equipped with pressure-controlled check valves that close when engine oil pressure drops below a prescribed value"

EAA_2014-03_not-so-plain-bearings.pdf (savvyaviation.com)

Busted Boost - Aviation Safety (aviationsafetymagazine.com)

Mike Busch notes:

Plain bearings rely on hydrodynamic lubrication to prevent metal-to-metal contact between the rotating journal and the stationary bearing. (See Figure 2.) Pressurized oil is pumped continuously into the gap between the journal and the bearing. This gap is only about 0.002 inch wide—about the thickness of a human hair. Rotation of the journal within the bearing, together with the viscosity of the oil, creates a dynamic wedge of high-pressure oil that keeps the parts separated. So long as the bearing gets adequate oil pressure and the journal rotates rapidly enough, there is no metal-to-metal contact and therefore no wear on either the bearing or the journal.

 Does this mean that plain bearings can last forever? Actually yes, provided the engine is run continuously (as it might be in a test cell) with an uninterrupted oil supply and uninterrupted journal rotation. Unfortunately, that’s not what happens in the real world. We start up our engines, run them for an hour or three while we’re flying from point A to point B, and then shut them down. It’s mainly those pesky startups and shutdowns that limit the useful life of plain bearings. When we first crank the engine, there’s no oil pressure and the crankshaft cranking speed is pathetically slow. The conditions for hydrodynamic lubrication simply do not exist. Consequently, there is metal-to-metal contact between the journal and the bearing, and wear is inevitable.  This startup wear is mitigated in several ways: The mating journal and bearing surfaces are polished as smooth as possible. The bearing surface is made of a material that has low sliding friction against the steel journal. Anti-wear additives in the oil react with the metal to form a thin protective film on the surfaces that further reduces friction through a phenomenon known as “boundary lubrication.” (See Figure 3.)

Figure 3

Edited September 17, 2022 by 1980Mooney

[GeeBee]

If he has engine data, a look might be in order when pressure went below minimums and how long that condition existed. An engine teardown might be required. In which case, the shops insurance would have to be notified. I had a PT-6 that went to zero but I caught it in time and shut it down that P&W said teardown not required. Might have to consult with Lycoming. 

[kortopates]

Typically, the turbo is the first thing to go with a loss of oil pressure; especially with slowly declining oil pressure. For one, the wastegate can need 45 psi or more to close it down to provide MAP.


Sent from my iPhone using Tapatalk

[A64Pilot]

I put a remote filter kit on my sailboat, reason was several fold, it enabled me to run a larger filter and and I could mount the filter vertical I could pre fill it, plus the big filter increased oil capacity, and I could change it with no mess. Win / Win, right?

Well I installed it, tested it, everything was fine, soon after leaving the marina I got a flickering oil PSI light, shut down the motor. Had a hell of a mess in the engine compt.

Looked it over and the O-ring had blown out of the adapter that screwed in place where the filter normally did, exactly what you have. Luckily I had extra oil and a spin on filter so added oil put a stock filter on and went back to the Marina.

Couldn't find anything wrong really so replaced the O-ring with a new one and tightened the adapter a little tighter just in case being loose allowed the O-ring to push out.

Went out the next day and Damnit it did it again, this time I threw the whole thing overboard and decided to stay with what Yanmar built. Oil all over the place. I don’t know, maybe the O-ring groove wasn’t cut deep enough?

With these kinds of things, what’s broken that we are fixing with them? Saving a few bucks at oil change?  I know filters are back ordered, but it seems if you need one somebody has one in their stash and will send it to you, great thing about the forum. I have had a case on order for a month or two, AC Spruce says maybe Nov. I think maybe when they come in I’ll order another case. I use about 3 a year so a case of six is a two year supply.

 

On edit, this is exactly what an SDR is for, your not doing anything but reporting a service difficulty, if your alone it won’t mean anything, but your report along with others could save someone some grief.

[larryb]

Regarding the tightening torque. For my factory filters I tighten by hand as tight as possible. Then use a wrench to tighten 3/4 turn past that. 1/4 tighten sounds way too loose to me.

[alextstone]

For those who are interested, here's some flight data:

 

 

Flight track:

 

8:15:22 am local, Manifold Pressure  and Oil Pressure begin to drop:

 

8:15:36 Manifold Pressure at 32.5 inches and I first recognize the problem

 

8:15:54 Turn back initiated and Oil Pressure near zero

 

8:16:10 Power Reduced to Idle in the decent

 

08:17:58 Shutdown of engine

 

 

[jetdriven]

You’re gonna have to tear it down.  I’d ask the oil filter mfr to pay the bill. 

[Shadrach]

3 hours ago, alextstone said:

For those who are interested, here's some flight data:

 

 

Flight track:

 

8:15:22 am local, Manifold Pressure  and Oil Pressure begin to drop:

 

8:15:36 Manifold Pressure at 32.5 inches and I first recognize the problem

 

8:15:54 Turn back initiated and Oil Pressure near zero

 

8:16:10 Power Reduced to Idle in the decent

 

08:17:58 Shutdown of engine

 

 

Uggh. I’m so sorry this is happened to you Alex, what a shitshow. Well done getting it turned around and down. A few links in the chain of this maintenance induced failure. It’s clear the seal design is defective. You would hope that would have been recognized by the installer. I don’t think the seal folded under pressure. I think it folded during installation and was nearly herniated when the leak check was performed. Heat and sustained pressure quickly brought things to an inevitable conclusion.

[alextstone]

31 minutes ago, jetdriven said:

You’re gonna have to tear it down.  I’d ask the oil filter mfr to pay the bill. 

Please explain further.  The engine was without oil pressure for 2 minutes and for the last minute it was at idle.  I am not questioning your expertise, rather asking you to educate me as to the decision.

[LANCECASPER]

I've always wanted a reason to buy one of these - mainly just for the ease of not having to cut open the filter, etc. And in recent times the shortages gave me another reason to look at them again. But two things have stopped me from doing it both times I looked, (1) the fact that it doesn't filter down to the same specs as a Tempest or Champion and (2) I did not like the o-ring - it looked like a problem waiting to happen.

The flat seal on a Tempest or Champion is a much better seal and has much more surface area than the very little surface area of the o-ring. Excellent job in getting the airplane down safely. The word needs to get out on this beyond Mooneyspace.