Kitfox 4 + HKS, the saga continues

[rwaltman]

Abstract:
I got my KF back from, or should I say, I rescued my KF from the A&P at the end of week 4 of the annual inspection. I don't understand what happened, this person has a good reputation and already did some minor work in the KF after I bought it.

Background:
The task at hand was, (1) condition inspection, (2) after a fuel leak, change the hoses in both wings, (3) after thinking about it, change all fuel and oil lines.
I asked for (1), (2) and (3) in successive days starting the week of July 4th , so we had a slow start, but still, this is a three day job, plus the time spent waiting for the hoses to arrive. One week and a half tops, two being very patient?
I got it at the end of week 4 for, after telling them I am not willing to wait any longer and I am taking it back regardless of the work being completed or not.

Last reports from the battle field:
I stopped briefly on my way to work on Thursday, was told “it's ready to go”.
I say I'm taking it the following day, they ask me to be there not later than 3pm. They also ask me to bring the cowlings from my hangar to run the engine with the right cooling, etc. I do that before leaving on Thursday.
Following day I call in the morning to make sure every thing is OK. (It is, of course.) I tell them I'll be there at 2:30. (No problem, we are ready.)
At 4pm I am still waiting while they are working on the plane #$*&%^! !
The cowlings on the floor, as I left them.

Finally they are done, I get the logbooks updated, load the cowlings in my car, pull the plane out of the hangar, unfold the wings (good, no leak.) The engine starts with a 2 second crank. They close the shop and leave.
I begin my own inspection, planning to do some taxi testing. Go around with paper towels cleaning the engine compartment, including the oil tank, the bottom is dirty. (They replaced one of the fittings)
I see a few minor things I asked were not done. In the logbooks, “HKS-700” is misspelled as “Rotax” (I printed all the manuals for them. HKS is all over the place)
I start and stop the engine a few times, (some problems here but not the A&P's fault, details later.)
A last check before taxiing out, one last go around with paper towels. The oil tank bottom is dirty. Again?
I look closer and find the oil drain bolt loose, not even “finger tight”, and not safety-wired …
Planning to have a serious talk with these guys on Monday.
Other than that,

Taxiing:
Next to impossible. The tailwheel unlocks and points sideways with very little side force, then the plane chooses which way to go without consulting with me.
Yes, I know the theory, a quick blast of power and use the rudder to straighten things out.
Yet, with untested brakes and taxiway lights plus other airplanes nearby did not want to try that theory.

The solution was already provided by Av8r3400 and others:

... Remove the unlocking cam from your Maule tailwheel until you are much more comfortable with the ground handling of your Kitfox. ... This cam unlocks the wheel allowing full swivel. If the rudder stops were not sized perfectly, the tailwheel will go to full swivel too easily and you'll have an instant ground loop.
Keeping the steering lock always engaged is much safer, at first.

Done, and now I can taxi. Just need to get one of those truck stickers: “Caution, this vehicle makes wide turns”

Engine:
To save some typing, just read Geowitz reports here [ http://www.teamkitfox.com/Forums/showthread.php?t=2995] and here [ http://www.teamkitfox.com/Forums/showthread.php?t=3803 ]

Relevant quote:

...on subsequent starts everything is rather violent and shakey until the prop gets up to speed. I mean bucking bronco type engine violence... Idle should be around 1600 rpm. At this speed the prop will go back into bucking mode with violence. Around 2000 rpm is somewhat bearable, but my panel is shaking like it's doing the jig. Above 2000 I can almost feel numbness in my body from the vibrations and see the panel shaking. It smooths out relatively above 3000 rpm and gets better the higher I go.

The numbers for me are different, but the tooth loosening vibration is the same. Unfortunately the Powerfin hub is 3-blade only, can not reconfigure it for 2 blades, to try a smaller MOI.
May bite the bullet and order a two-blade hub until I decide what to do. Anybody has an unused 2 blade wooden prop I could buy cheap?

A couple of bright spots:
(1) The battery survived the 2+ years deep discharge.
(2) The engine starts in 2-3 seconds when cold. Slightly warm, it starts instantly. Not fast, not quickly, instantly. I don't think the propeller does more than 1/2 a turn from turning the starter to running on its own.

Next steps:
1st, the quality of the inspection being in doubt I'll do my own using the Kitfox Aircraft provided item list as a guide. May recruit some more knowledgeable friends.

2nd, the engine vibration issue. The previous owners flew from small grass fields with zero traffic, minimizing the time the engine needs to run at idle or low power. I have a longer taxi, may have to wait for other traffic, etc., needing to be above 2400 or 2500 to stop the shaking.
At this high idle rpm the propeller generates too much thrust. Not only staying put requires using the brakes, I need to brake also to keep the taxi speed at a reasonable level.
I see a new propeller in the future...

To be continued.

[napierm]

Sorry the condition inspection went so bad. When I got the KFIII I spent several months (I'm slow) changing out all the rubber, re-sloshing the tank, changing out the crank in the 582, replacing worn hardware, cleaning and re-greasing anything that moved, etc. Stripped and repainted a few things as well. Then the condition inspection was a retired A/P I knew who gave it a once over and kept commenting on how nice it looked and then told me what all to write into the log book before he added his language to it. I think being able to do all the work on these planes and being sure its done right is one of the best perks.

Then when it started flying (yes!) I had to spent more time figuring out how to set up the jets and and tuning lots of other things that had never been done on that plane plus learning how to fly it (slow feet). Well worth it, put over 200 hours in the KF and had a great time. Crap, I wish I had something flying right now....

What gear ratio do you have? I sold off my Powerfin (it was a pusher) but it was a pretty good match for my HKS 3.47 gearbox according to the previous owner. I do recall that the Powerfin is pretty light weight. You could measure the inertia to see if it is over/near the limit. One guy is running a 74" 2-bladed wood prop on his Avid Flyer using a 2.58 ratio HKS with good success. He is on the Yahoo HKS group.

I keep collecting new/used props. I've got a 70" Kiev, a 70" 2-blade IVO medium (minus the front hub, anybody have one?), and a 70" 3-blade tapered Warp Drive (supposedly came off a Subaru, but has a 100mm bolt circle and a 1" hole). When I ever get to fly I'll have a few to try.

You have the Lost Hills motor mount as well, yes? You might call MNFLYER and trade notes. He's been pretty helpful to me. He used to have the 3-bladed warp drive prop on his and I know mine is pretty heavy. I don't recall him mentioning the vibration you have. Are the carbs synced? From your description I wouldn't count on those mechanics and would check it myself. That can make it shake.

Can also check the balance, pitch, and tracking of the prop. If I recall right the Powerfin had a 1" hole front and back. If so, checking the balance is easy: a 1" tube and two lawn chairs work very well. Mine are all different and so had to make a few spacers. If these are off only slightly it is not going to give the hard vibration you are describing but its worth a check.

Best of luck,

Mark

[Geowitz]

I would second the motion on the carb sync. Perhaps you already did this, but I don't recall you noting that as being done. That's always first on the HKS engine vibration check list.

As Mark said, the powerfin's are pretty light and there are a lot of people using them on the HKS's. I wouldn't give up on it just yet.

[Mnflyer]

Hi Robert, also when starting the engine I only turn on the electic pump to fill the carb bowls and to hear that its running then I turn it off when cranking the engine I have notice significant engine smoothness starting this way the electric pump tends to flood the engine when starting and until the excess fuel is cleared out the engine runs extremely erratic / ruff, and syn the carbs.

[rwaltman]

Are the carbs synced?

I would second the motion on the carb sync.

and sync the carbs.

OK, OK, I got it. I'm buying a Carbmate.

Roberto.

[rwaltman]

1 ... What gear ratio do you have?
2 ... I do recall that the Powerfin is pretty light weight.
3 ... You could measure the inertia to see if it is over/near the limit.
4 ... You have the Lost Hills motor mount as well
5 ... Are the carbs synced?
6 ... check the balance, pitch, and tracking of the prop.
7 ... Best of luck

1 - I believe is the 3.47:1 - Will check
2 - That's the claim. Around 0.75 Kg per blade.
3 - In my to-do list - From Powerfin's web site:
"POWERFIN Propellers are 2,500 kg/cm2 for a big three-blade model and 1,800 kg/cm2 for a two- blade model."
4 - Yes.
5 - In my to-do list - I asked this to be done, don't know if it was done, and wouldn't trust the answer anyway.
6 - Did check the tracking (with a very rudimentary setup), waiting on a new torque wrench to do more.
7 - Thank you!

Roberto.

[rwaltman]

Today's update - Did around 25 minutes taxiing, without the tailwheel unlock it felt very much under control. Of course, I did not run very fast or rise the tail. And most of the time dragging the brakes.
Can make a U-turn in two fuselage lengths (roughly, less?)
I was paying more attention at the taxiway lights than at the turn radius, believe could make it better with some practice.

Found the previous owner(s) check list. It says after engine startup, warmup while idling at 2000 rpm. Cannot do that without "the shakes".
At 2200,2300 rpm begins to be OK.

But it did not feel as bad as last time. Followed Mnflyer suggestion of not using the fuel pump; was more proactive correcting the throttle; also let the engine reach higher temps.

More squawks: One CHT stoped working. The oil temp is erratic, goes up and down, shows zero, climbs again. Neither one of the fuel gauges (installed in the wing roots, not the panel) work.
The tension spring on the pilots side left rudder pedal falls. (too long? overstretched?)

[ Still thinking if I should stop payment on the check with which I paid for the inspection etc. Probable have only a few more hours to do so. ]

I am planing to do several hours taxiing, will try to put at least 45 minutes every day after work. Can/should I log this time as PIC, even though I have no intention of taking off?

To be continued.

Roberto.

PS: Added pics of the engine installation here: http://www.teamkitfox.com/Forums/album.php?albumid=117

[tommg13780]

Roberto,
Have you considered putting a little more time into problem solving rather than typing??????????

[Geowitz]

OK, OK, I got it. I'm buying a Carbmate.

Roberto.

Especially with the 3.47 gear box you should be silky smooth with that prop.

[rwaltman]

... should be silky smooth with that prop.

Hopefully, but I never read of anybody idling at 1600 rpm with that engine/prop combo ...

Roberto.