Why a second set of eyes - and hands...

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.

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Wm.Ince
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Re: Why a second set of eyes - and hands...

Post by Wm.Ince »

drseti wrote:Eddie, please remember to do a full oil system pressure purge after working on the oil pump. And remove the rocker box covers afterwards, so you can make sure all the lifters have inflated by pushing in on the rocker arms.
Excellent reminder.
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Re: Why a second set of eyes - and hands...

Post by roger lee »

So long as the only oil lost is in the pump then all you need to do is a vent and not a full system purge. This is no different than using the old oil filter that had a check valve in it and the oil filter could not be pre-filled. To fill the old filter with oil you were supposed to vent the system. The oil pump is a positive displacement pump and self priming. So long as the spark plugs are all in place then you can just rotate the prop about 20 times and it will prime and vent the pump from any air. The amount of air in the pump is no big deal so long as you vent it.

p.s.
5 years ago I did a research project on documentation. I had the FAA vet 12 logbook entries. (yes they know who you guys are now :)) I sent 3 of my logbook labels in with them. The bottom line. The guys who only put in 3-4 lines for an annual are at the bottom 1% -5%. The FAA says what's is the regulations for documentation is the bare minimum. All three of my labels were at the top of their list and they wished others would do a far better job in documentation. This document is published on the Rotax-Owner forum in the blogs.

Quit striving to be below or even average because there are way too many of those folks out there, but strive to be a cut above the others. It only takes a couple minutes more and it will go a long way in protecting you from the FAA, Insurance companies and litigation from passengers and or people on the ground. It protects both owner and mechanic. Remember what ever your mechanic does or doesn't do you also get held responsible for.
Roger Lee
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Re: Why a second set of eyes - and hands...

Post by Wm.Ince »

roger lee wrote: . . . . . you can just rotate the prop about 20 times and it will prime and vent the pump from any air.
Regarding “20 times,” does that mean 20 complete prop revolutions (60 blades), or 20 blade advances?
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Re: Why a second set of eyes - and hands...

Post by roger lee »

Yes, 20 complete revolutions. There isn't much oil volume in the pump, but you don't want to start it dry.
Roger Lee
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Re: Why a second set of eyes - and hands...

Post by Wm.Ince »

roger lee wrote:Yes, 20 complete revolutions. There isn't much oil volume in the pump, but you don't want to start it dry.
What is the best technique for pre-filling the new oil filter during a filter change?
How full should the pre-fill be?
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Re: Why a second set of eyes - and hands...

Post by roger lee »

I fill it to the top 3 times. It will settle out into the media and the hollow area outside the media. Then just screw it on. Done.
Number one problem I'm seeing is over tightening. Takes Godzilla to get them off.
Screw it on until it touches and then just 3/4 turn more.
Roger Lee
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Re: Why a second set of eyes - and hands...

Post by Wm.Ince »

roger lee wrote:I fill it to the top 3 times. It will settle out into the media and the hollow area outside the media. Then just screw it on. Done.
Number one problem I'm seeing is over tightening. Takes Godzilla to get them off.
Screw it on until it touches and then just 3/4 turn more.
Thanks Roger . . . on your technique . . . for filling with oil. I’ll try that next time.
As far as tightening, the directions say just as you instructed, (270°), but once the engine is started and the temps come up, it makes the filter even tighter. According to Dean Vogel (at Lockwood) . . . that tightness you observe is normal. It’s just the character of the beast. Mine are always a bugger to remove (unscrew) also.
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Re: Why a second set of eyes - and hands...

Post by FastEddieB »

Filling an oil filter is a good idea, on planes, cars, motorcycles or whatever. It slightly reduces the time the engine may run with little or no oil pressure, which is a good thing. Of course, difficult to do when the filter mounts vertically “upside down” like on many aircraft engines.

One thing I’m having trouble understanding...

The worst thing regarding wear is to drag unlubricated parts over each other in the absence of lubricant and/or oil pressure. I’m not sure why doing this slowly is better than doing it quickly. And the quickest way to get oil pressure and get things properly lubed is to just start the damn thing - or so it seems to me. It’s one reason I burp my engine and check the oil level right after a flight* - it only takes maybe a dozen or so “blades” to get the burp as opposed to nearly 30 when cold. And again, how much unnecessary wear is occurring during those 30 blades sans significant oil pressure?

Anyway, the vast, vast majority of engines of all types and configurations just get started after oil changes, to no apparent ill effect. I’m wondering if there’s anything documented as to why our engines might somehow be different in this regard?

Back on topic, the muffler got back to the mechanic from Lockwood yesterday. We’re still waiting for the oil pump shaft, which apparently needed replacement and was not easy to find in stock. And I’m starting to miss my little plane!


*My plane is hangared and I’m the only one flying it. I do realize that checking the oil level before each flight is SOP and generally the best practice.
Fast Eddie B.
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Re: Why a second set of eyes - and hands...

Post by FastEddieB »

Photos of the repaired muffler:

Image

Image

I asked if there was anything I might have done that contributed. He said no, it was just a high stress area that he had seen fail before, more commonly on planes runnIng 100LL (mine runs about 95%+ on MOGAS). I believe the Professor has had cracking exhaust issues and invite comments.
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Re: Why a second set of eyes - and hands...

Post by Warmi »

Interesting ....what is that wrap you got there on the pipe and where do you get it ? ( hopefully at Home Depot :-) )
Flying Sting S4 ( N184WA ) out of Illinois
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Re: Why a second set of eyes - and hands...

Post by Nomore767 »

Was down at my mechanics hangar today and I got to admire Fast Eddies Sky Arrow!
Very nice!
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Re: Why a second set of eyes - and hands...

Post by FastEddieB »

Warmi wrote:Interesting ....what is that wrap you got there on the pipe and where do you get it ? ( hopefully at Home Depot :-) )
It’s exhaust pipe wrap. I got mine at O’Reily’s.

I think it’s been discussed here and/or on the CTFlier forum.

Two alleged benefits:

1) A tiny increase in performance. The idea is hot exhaust gasses exit the exhaust more energetically, causing slightly less back pressure. But as I said, it’s a tiny gain and I didn’t notice any increase in performance. Still, it could conceivably make the difference between clearing a tree line or not, let’s say, so any gain is welcome.

2) It keeps temperatures under the cowl lower. This is especially important in a pusher prop configuration, since there’s no huge fan in front of the engine pushing air over it when stationary or taxiing*.


*In lieu of the “big fan”, the Sky Arrow does have two small electric fans in front the radiator and oil cooler. It can get really hot without them during extended ground operations.
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Re: Why a second set of eyes - and hands...

Post by FastEddieB »

Nomore767 wrote:Was down at my mechanics hangar today and I got to admire Fast Eddies Sky Arrow!
Very nice!
Thanks! Are you based near there? And has Dana worked on your plane?
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Re: Why a second set of eyes - and hands...

Post by Nomore767 »

Dana has been my mechanic for several years and I was pleased to find a Rotax trained and qualified mechanic to maintain my plane.
I’m based about 30 minutes flying time at KFDW Fairfield County.
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Re: Why a second set of eyes - and hands...

Post by FastEddieB »

Update...

The work is complete, the oil leak apparently fixed, and the invoice prepared.

The actual rubber parts replacement was $2,950. This included a small allowance for the fuel lines I had already replaced. It's about 50% more than when Roger did mine 7 years ago, IIRC, but fair for inflation I think.

There were 12.5 extra hours of labor for the muffler, mounts, oil tank, oil pump repair, etc. $937.50

With the actual muffler repair (only $75!) and misc shipping and supplies, the total was about $4,360.

For perspective, in 12 years of ownership, this is the biggest single maintenance expense I've had.

Going back a few years to just after that last rubber parts replacement, here's what my Sky Arrow has cost in maintenance and parts by year:

2018: $297.96
2017: $513.79
2016: $584.22
2015: $160.98
2014: $55.62
2013: $296.43

Figure roughly 40 hours/year on average. Not bad.

Anticipating for those doing the mental math, yes, I ended uo going for more than 5 years on the rubber parts. Being Experimental, its at my discretion. But, of course, The Most Conservative Action is to abide by the ROTAX requirements, even if not legally required to do so.

I'm eager to get the little plane back. With conflicting schedules, July 7 is about the earliest I'll be able to make it over. The plan is to drive over with Karen (about 4 hours each way), take off and fly over the airport for an hour, land, de-cowl and inspect, and only then both start the trip home. Some pretty rough terrain between there and home, so better safe than sorry!
Fast Eddie B.
Sky Arrow 600 E-LSA • N467SA
CFI, CFII, CFIME
[email protected]
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