Re: Model 2 Header tank, re: SB 29
Hi Jacob, congrats on the purchase of your Kitfox, sorry to hear of the fuel problem. Glad to hear all turned out ok with the off field landing. Is the header tank you are asking about the round alum. one that mounted ahead of the inst. panel? or are you looking for one that mount behind the seat?
Re: Model 2 Header tank, re: SB 29
This issue has me confused.
I have a flying mod 1 and totally rebuilt it. I mounted the plastic
header tank behind the firewall to lesson the fuel lines inside the cabin.
The tank is vented back to both wing tanks and there has never been a fuel
problem with this setup.
I don't have SB 29
What was the problem that created the modification bulliton???
Bob
Re: Model 2 Header tank, re: SB 29
This is the original service letter
http://www.kitfoxaircraft.com/suppor...tters/sl22.htm
and the follow-up MANDATORY service bulletin which applies to all models prior to 12-08-1992 is here:
http://www.kitfoxaircraft.com/suppor...etins/sb29.htm
Hope this keeps you out of the hay field unless that's where you want to land.
JP
Re: Model 2 Header tank, re: SB 29
One thing that comes to mind for this thread is using an early warning (low fuel) indicator at the header tank. I know Murle Williams has them here but I didn't see them on John's site (he may carry them). These come with a warning light that is easily installed on the panel...Gives you a little time to get the plane on the ground.
FWIW
Re: Model 2 Header tank, re: SB 29
I did have a problem
when the header tk was only vented to one tk.
It was not he header tk installation but on the tank not vented
to the header tk fuel line. Whih the wing in flight position the fuel line
was partially kinking, just enough to restrict flow.
The fuel burn was more than the flow and it got real quiet which
was nice but puckery. I opened the other tank and the noise came back
I put a small coil spring inside both fuel lines leaving the tank and the line cannot kink and no further problem. I got this idea from a skidoo 670, which had springs inside the fuel lines, also the oil lines.
Re: Model 2 Header tank, re: SB 29
lasercon
There are several items addressed in Service Letter 22 that may be pertinent to your aircraft. Follow the recommendations on fuel line routing and venting.
Also be sure you comply with Service Bulletin 29.
JP
Re: Model 2 Header tank, re: SB 29
Why do you reccomend complance with these service letters?
My system works fine and I didn't buy anything to fix it.
How can a system that has fuel lines 20" +/- below the fuel pump
and with 10ft more fuel lines inside the cabin work better?
Re: Model 2 Header tank, re: SB 29
Bob,
Thanks for the opportunity to respond to your question about whether you should comply with service bulletins and service letters.
Let me preface my reply with a quick note. Often, emails and postings can sound a bit harsh. It’s hard to know the tone of the person doing the posting. I do not want to sound like I am pontificating or flaming you in any way. Just read this as if we are two aviators having a cool drink under the wing of your airplane in a friendly discussion.
You asked why should you comply with service letters and service bulletins when your plane is working fine. The real question is, “Why would you not want to comply?”
When a manufacturer of certified aircraft or kit supplier identifies a problem they notify all users via service letters and service bulletins.
A service letter indicates there may be a problem and operators should investigate and inspect their aircraft. Service letters often include possible remedies. A service bulletin is a red flag saying there is a definite problem and compliance is mandatory for safety. An airworthiness directive [AD] is when the FAA steps in and says you must comply or your aircraft will be grounded. (AD’s do apply to homebuilts. Just ask the owners of the Zenair 601)
When your aircraft is up for annual inspection, either your mechanic, or you as the certified repairman must sign in the logbook that the aircraft is airworthy. This means you have inspected the aircraft and researched any letters, bulletins and directives that may apply to your aircraft. It is your responsibility to ensure compliance with service letters, bulletins and directives. As the operator, you must ensure that the logbook indicates required maintenance and inspections were performed.
A fuel flow problem was identified with early Kitfox aircraft. Not all aircraft experienced a problem every flight. Some never reported a problem. While your aircraft may have operated without fault for the last 100 flights, can you be sure it will operate OK on flight 101? The simple fact is this: fuel starvation can occur, and there is a fix.
If you do have a fuel delivery failure resulting in a damaged aircraft or bodily injury, and investigation reveals you did not comply with the service bulletin; your insurance may be void, You may be personally liable for damages. You also may be subject to a violation under 91,9 for careless and reckless operation. The key issue is you are now aware the bulletin exists.
Aviation is not without risks. We do our best to minimize those risks. To ignore it because you think your aircraft is working fine is not the wisest choice, even if the risk is remote.
About 15 years ago TWA 800 exploded and went into the ocean off Long Island. It appears a fuel pump caused a spark in a near empty center tank. The same type of pump was used in 737, 747, 757, and 767. They had logged millions of flights and multi-millions of hours without a problem. The odds of it happening again are extremely remote. And still, those odds are unacceptable. All of the Boeing aircraft are affected by an AD to prevent that remote possibility.
The same goes for your Kitfox. Any known possibility of fuel starvation is an unacceptable risk. The key word here is “known”. This is not a theory on how it might happen, it is a report of several fuel starvation incidents. The modification to prevent it is neither difficult nor terribly expensive.
As to the actual installation and modification, the fuel pump doesn’t have to suck up fuel from way below your present location. There is positive fuel flow or head pressure to the pump inlet. In fact, my Kitfox doesn’t even have a fuel pump. Gravity works just fine.
The rear header tank location provides sufficient fuel drop to ensure proper venting. That occurs because of higher head pressure at the tank. It also creates a superior place for water condensation removal.
The additional length fuel lines are probably less risk of fuel leaks. Most leaks occur at fittings and valves. The modification reduces the connections by eliminating individual wing valves, if installed.
The revised fuel line routing goes under the door instead of over it. The loop over the door created a "p-trap" in the vent line.much like your kitchen sink.
With fuel going under the door, a fuel line leak will likely drip out the bottom of the aircraft instead of on your shoulder.
While the above is a somewhat lengthy reply, I hope you take it in a friendly tone and consider it merits. It is not meant to be derogatory in any way. I hope you will modify your aircraft and enjoy many hours of trouble free flying.
Regards,
John Pitkin
Greenville, TX
Re: Model 2 Header tank, re: SB 29
great explanation john , but how can you be sure it wasnt a missile that took down twa 800 ?