Chinook Plus 2 - Fuel Questions...

1. Which fuel tanks should I use first?
My preference and advice is to use your fuel selector to select RH or LH strut tank. The 3rd choice is to select in-wing tanks which are plumb together. You would be flying on either the RH or LH strut tank or both in-wing tanks at any one time. We advise that if you are flying with the in-wing tanks, that on your take off and landing, that you would be using the strut tanks but when flying, that you would switch to your in-wing tanks. The in-wing tanks have been designed as auxiliary tanks to your strut tanks and there is no way to gauge the fuel in your in-wing tanks. To make sure that you always have plenty of fuel on board, always have fuel in all 4 tanks if going on a long distance trip. If you are not going to be flying any long distances, we suggest that you don’t even fill the in-wing tanks and only run your strut tanks. Remember the in-wing tanks are only auxiliary tanks and should not be used as the only source of fuel. (See the memorandum in question 3) - back to top

2. Where do I locate the selector valve? 
Your selector valve location is customer preference. See attached pictures. - back to top

3. Are there any limitations with the Chinook Plus 2 supplementary in-wing tanks? 
Read the following Memorandum dated March 20, 2004. 

Memorandum - 20 March 2004 - Chinook Plus 2 In-Wing Fuel Tank Kit Advisory

Applicability: Users of Chinook Plus 2 aircraft with optional in-wing tanks

Effective: Immediately

Purpose: This memo is designed to advise users of Chinook Plus 2 supplementary in-wing tanks on updated operational limitations.

Background: The in-wing fuel tank option is popular with Chinook owners for extending the endurance of their aircraft, more than doubling total fuel capacity versus strut tanks alone.
The in-wing tanks are mounted above the wing drag/anti-drag braces and below the wing ribs with the root ends visible inside the cabin. Fuel leaves the tanks via two points on the root end of the in-wing tank, one located at the front and one at the rear of the tank.
The in-wing tanks have always been marketed as supplemental to the strut-mounted tanks. As of this writing, there has been only a single Chinook Plus 2 sold without the standard strut-mounted fuel tanks. The original builder of this aircraft elected to substitute the in-wing tank kit for the strut tanks for aesthetic reasons. During the course of his flying, no adverse effects of using these tanks were experienced.

Source of the Advisory:
The aircraft was subsequently sold to a flight training unit to be subjected regularly to stalls, steep turns, extended climbs and descents and side-slips.
Prior to use in the training environment, it was determined in certain flight attitudes the fuel pickup points of the in-wing tanks could be exposed to air, allowing air to be drawn in to the fuel lines.
This occurred with less than full tanks; the exact amount of remaining fuel was unknown. The condition was noted as bubbles appeared to travel from the in-wing tanks along the fuel lines. This could eventually have led to the float bowls emptying sufficiently to starve the engine of fuel. Returning the aircraft to a straight and level attitude while the engine was running would allow fuel to cover the pickup points and re-fill fuel lines.

Procedure Change:
Chinook owners are advised to use in-wing tanks for level cruise flight only. During take-off or landing or any flight attitude where fuel could be drawn by gravity away from the front or rear root end fuel pick-ups, the in-wing tanks should not be used as a fuel source. Instead, the standard strut-mounted tanks with integrated flop tubes should be used.

Conclusion:
By following this procedure, the in-wing tanks may continue to be used as they were intended as supplemental tanks for extending the Chinooks endurance. - back to top

4. Where do I mount plate 10-37 for the 3-way valve?
Mount it to the 2-044 with rivets. - back to top

5. How do I install in wing tanks? 
Put the tank in first then do the covering. Shrink the fabric and then place a patch over the fabric (4" to 5" diameter) to strengthen around the hole you will make. You can then make a hole and place the threaded part in and decide how high you want the other part to be. The part of the cap that does not have the threads will stick out above the wing unless you cut it really short. See the attached pictures. - back to top

6. What would be the possible cause of discovering water in my fuel system?
It could be either bad fuel or a sealant was not used on the threaded section of the pipe that goes into the tank. The Perko pipe inserts into the ABS part and must be sealed. Use a little teflon tape around the threads. If that seal is broken, water could run from the wing under the Perko pipe flange, down the pipe and through the broken seal into the tank. It could also be bad fuel. - back to top

 

Well, we hope that we have clarified a few of your questions. If you do require additional assistance, we would be very happy to hear from you with your questions, comments or concerns.

 

ATTENTION: We answer all our e-mails promptly within 24 - 48 hours and if you have not heard from us, it is possible that your e-mail has landed in our SPAM mail. Please, if you have not heard from us within that time frame, send the e-mail again or call us at 250-549-1102.