Kitfox-4 elevator trim systems, rans wheel or electric ???

[rogerh12]

FYI on the Rans wheel trim. Rans released a scary notice saying that it has led to elevator flutter, due to the usage of a spring in the trim system.
They have recommended going to an electronic servo type trim system, with a ridged pushrod arm, or a mechanical system one with a ridged push rod or tube.

[catz631]

Roger,
I sent my 4 elevator off to Lowell at Highwing LLC and had him install the elevator trim. I installed the trim button in my stick and I now have a terrific system !!! No more "mickey mouse' flap trim. Its really great to trim the pressure off on approach as well as level flight. This is the only way to go !!
Dick

[napierm]

WRT to Rans Trim Wheel, I'm installing one of those. There is no spring in the system. It uses a solid wire push/pull system. Eric Ashman has one on his IV and it works great.



What *is* a concern on these push/pull systems is to make sure the wire and sheath are secure.


What I've use on these cables is safety wire on the outside as well as Loctite "Black Max" 380 adhesive. This will bond the sheath to the wire as well as to the metal locking ferrule.

Just me, I like the mechanical trim more than an electric servo.

Cheers,

Mark Napier

[Av8r3400]

Here's the RANS trim system from Spruce.

What I like about this is the tab can be attached to the rear of the elevator not needing covering repair or cutting / welding. Plus the wheel is a nice infinite adjustment.

[rogerh12]

Looks like I saw the faulty trim system notice Rans put out on the old trim system, and agree it does not include the current system offered by aircraft spruce.

Regarding the crash after a trim system failed; from a guy that flew a plane and landed safely after his propeller broke off,,, losing power and panicking does not have to equal stall and crash, (neither does a stuck trim tab), if you remember to fly the plane while your panicking. I know you don't want too, because that’s where the ground is, but keep the nose down during all maneuvers, and you won't stall the plane. A controlled crash is 10x better than stall and crash.

Roger

[napierm]

The trim tab brackets don't require welding, but some hammering over a steel rod and cursing are in order. The radius of the Rans aluminum tubs is much larger than the steel tube trailing edge of the Kitfox. Also, I still need to make an appropriate spacer to put the cable retainer at the right height to lay right on the fabric. I know it is on the bottom but I still want it to look good.

About that NTSB report, there is a local guy who had a departure stall in a Kitfox Lite and dropped in about 50 feet. He broke his shin bone badly. The medication that the paramedics gave him for pain blocks the formation of short term memory. So just like the guy in the NTSB report, he couldn't remember the details of the take off and stall or much else that went on that day. So I can't 2nd guess what happened that caused the stall with the bad trim system but I can make darn sure that my trim system is right. If the force required to keep that stick forward was too great I would also be tempted to slow the plane down to keep from breaking something in the control linkage.

There is another report in the NTSB where the stick in a Kitfox IV wouldn't go to the left of center. The guy got it down with rudder but lost it on roll out. He was unhurt but trashed the plane. They didn't say but I would bet real money that the little bell crank under the seat was catching on the floorboard/carpet. Mine is going to have a hard steel ramp right there on the floorboard and a stout screw (maybe safety wired) holding onto that floorboard/fuselage attachment bracket just under the bell crank.

FWIW,

Mark

[rogerh12]

Does anyone have pictures of the RANs elevator trim tab installed?