Pilot report on Aviation Enterprises internal wing tanks:

[sloutitt]

Pilot report on Aviation Enterprises internal wing tanks:

As a replacement for the external wing tip extensions that have recently come under an AD we looked at the A.E. internal units. Our plane is a 1973 T337G ( I Think they refer to this as the short wing plane) It has stock 125 gallon tanks (123 gallons usable). After removing the wing tip extensions we lost enough range that we needed to find an alternative.
Our early discussions with Owen Bell were frank and forth right, Owen gave us an estimated cost that was based on his shop supplying the parts, labor and STC. We requested to have a shop closer to home do the work in order to enable me to better administer the process. Owen agreed and we settled on a price for the STC and supply of the required parts and tank manufacture. Owen Delivered the parts and instructions as agreed and on time. We had an issue with a dead fuel probe which he offered to promptly replace under warranty.
The tanks are separated into 4 tanks two inner and two outer tanks on each wing. The inner tanks hold 12 gallons with 11 usable, the outer tanks hold 8 gallons with 7 usable.

The good:
The installations instructions and process seemed to go smooth, which was surprising as this was the first time both for my shop and Owen who had typically only done this install in his shop so the instructions had to be augmented to enable a third part to have better understanding of the process. The loading options with two aux tanks are now more flexible and somewhat easier to manage as you can just fill up the tanks you really need and be confident about exactly how much fuel you have on board (I never trust fuel indicators). The AD required the wing to be open for inspection so some of the labor for the tank install was offset in the AD anyhow. The tanks, transfer pumps and fuel gauges all work as advertised and the plane now has much better roll rate without the wing tip extension tanks on. Since install I have flown approx 30 + hours on new system including a trip from Canada to Mexico and back.

The Bad:
It aint cheap. You have to really want the range to pay this price. My final all in bill was close to 50k Canadian. Granted I suspect that the process will get cheaper for newer installs. I had to pay for learning on both sides so I assume there was some efficiency loss there. My shop complained that Owen’s tanks had rough top edges that made it hard to seal the tanks once they were put in place. Owen complained that the shop did not communicate their problems and process to him so he could better advise them.
Final thoughts:
Operationally we are happy with the mod. Financially it may not make sense to a lot of people.
Sandy Loutitt,
N81C based at CYBW
If my work schedule allows I will try to attend the gathering in Dayton

[hharney]

Sandy
Thanks for your report. Could you share the number of hours labor to install the mod? All 4 tanks. Are the tanks composite? Are there any restrictions to airspeed or which tanks can be filled or full or empty?

[sloutitt]

To remove the old wing tips and comply with the ad was 48hrs,
366 hours for install of new tanks shop rate is 80/hr
There are no loading or air speed restrictions to stock, which has really impoved my decents as we live right next to the mountians so arriving from the west with a MEA of 16k within 30 miles of the destination airport makes for steep decents.
I should note that I was very cautions about flying within the posted limites on the old wing tanks (obvously so was the second owner) and when the wings were pealed back for the AD inspection there was no sign of damage at all anywhere.
The tanks are composite, I assume glass and maybe a little carbon fiber. Each tank sits in the void section of the wing, these are the same spaces that the stock ling range tanks occupy so I think that is why there was no flight or loading restrictions.
The tanks are configured with an inner and outer independent tank on each wing. They use transfer pumps to move fuel to the main tanks.
Hope this answers the questions. I will try to attach a few pictures for clarity.