Author Topic: FEEDBACK NEEDED ABOUT WOBBLE PUMP REPLACEMENT OPTIONS  (Read 920 times)

Robert Wiley

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FEEDBACK NEEDED ABOUT WOBBLE PUMP REPLACEMENT OPTIONS
« on: April 17, 2012, 04:39:13 PM »
To all my fellow  E series owners with the later model wobble pump,

I would like all that would read this and provide me some feedback and opinions. I recently experienced problems with my wobble pump not performing. My A&P has replaced the o-rings but noticed at least one of the check balls is worn. I contacted ABS (Neal) and he advised finding used parts. Raytheon has these balls for $100 each and theres are six in the unit. I also inquired of a shop to overhaul at $650 and that is not including any check ball replacement. That led me down a path with a company interested in a possible kit of parts to rebuild the pump including the check balls. They are currently using my pump to reverse engineer the entire pump / selector assembly. I am trying to compile a marketing analysis of possible owners of E series aircraft interested in one of the following.

1) a rebuild kit
2) a redesigned wobble unit alone
3) a redesigned wobble unit with new boost pump integrated.

I would like all input I can get to make a determination if this venture would make sense to economically incorporate.

I know there are many who want to keep there aircraft as original as possible but we all have seen and experienced the same road blocks on other components on our aircraft. I am just trying help our community interested in keeping these well designed birds flying at affordable prices.

Thank you for listening. I am very interested in all input positive or negative.

I do not want to congest the forum so please email me with the following at rswiley@fpunet.com.

1) Which item would interest you or multiple items.
2) Your aircraft model and sn
3) Your cost threshold for the items you would pay.

Lewis Gage

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Re: FEEDBACK NEEDED ABOUT WOBBLE PUMP REPLACEMENT OPTIONS
« Reply #1 on: April 20, 2012, 06:38:25 PM »
Dear Mr. Wiley,

A modification of the fuel system to the degree you speak of would require a field approval or one time STC for your airplane alone or a blanket STC to cover all of the old V tails. Any of these would not be easy to get.

The standard wobble pump setup, especially the later style pump that does not use the fuel selector valve handle as the pump handle (early style pump installed on D1 through D2900, late style pump D2901 through D4865) does the job intended. Some early style pumps have been replaced with the late style pumps. Only the late style wobble pumps use the ball check valves.

Although I have an aux electric pump installed on my G-35 I never use it for starting, only the manual wobble pump for that chore. However, if the engine driven pump (TF 1900) were to fail the electric aux pump would be very handy.

Depending on the degree of wear you mentioned on the check balls, they may be able to be reconditioned so they are servicable. Years ago, I overhauled the wobble pump in my G-35 and refinished several of the balls, using a drill press and some fine grit paper. As I recall it took only very light sanding to do the job and they have been working as new ones would for the many years since that time. Unless the stem of the ball were broken off they could probably be used after some rework.

Regards,  Lew Gage   

Lewis Gage

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Re: FEEDBACK NEEDED ABOUT WOBBLE PUMP REPLACEMENT OPTIONS
« Reply #2 on: April 20, 2012, 06:43:04 PM »
One other thing, you would also have to get the PMA to produce the parts for sale or the vendor would have to do so and you get approval to install the said parts on an airplane via the STC process.

Regards,  Lew Gage