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Boost Pump

Posted: Fri Mar 25, 2011 10:17 pm
by Fred
We've discussed this before but I'll through it out their again. I have approx 700 Tach and looks like I need to replace my boost pump (This will be the fourth!). I use the fuel pump on TO and Landing (as I take the runway, and on short final I Push the prop forward and hit the boost pump).

On the other Diamond board last year this was discussed and many DA40 owners had low life on their fuel pumps.

Does anyone else have an issue and need a new fuel pump with this kind of frequency? I average 250-300 Hobb hours per pump.... First pump changed out at 120 tach.

Also do you buy new, or referbished pumps; and at what cost?


Thanks in advace, Fred

Re: Boost Pump

Posted: Fri Mar 25, 2011 11:35 pm
by Jean
Hi Fred,
Our boost pump has 932 hours and no problem.

Re: Boost Pump

Posted: Sat Mar 26, 2011 12:49 am
by Rich
I've replaced twice, each at around 400 hours and 52 months. I just had one rebuilt to "revision B" by Dukes and installed it. They believe this revision solves the short lifetime issue found in so many pumps, but this redesign is only a few months old and not much field experience exists.

Give Dukes chapter and verse on your difficulties. I did this (avoid crucifixion language) and they gave me a substantial break on the rebuild.

While a few here say they've had satisfactory lifetimes from theirs, there are plenty of us that have not.

Re: Boost Pump

Posted: Sat Mar 26, 2011 12:59 am
by Chris
We've been lucky so far with 500+ TT on our first pump.

Re: Boost Pump

Posted: Sat Mar 26, 2011 1:19 am
by Fred
A bad pump I can see, but 3 for 3 has me wondering. I shut it off after TO @ 1,000 AGL, and only turn it back on short final.

Just don't know... I'll try the new Duke pump mentioned if it is a subsitute for our da40

Thanks!
Fred

Re: Boost Pump

Posted: Sat Mar 26, 2011 12:00 pm
by Erik
There seems to be some planes that go through lots of pumps faster than others, just from the anecdotal evidence I have seen on the two forums. My plane went 1600hrs before the first pump blew - and in real terms for a $1k pump even that is too much, but I am lucky compared to the several others who have had like Fred, many pumps blowing one after the other. I am not the only one to go well over a 1000hrs on my pump from either, as evidenced by reports some reports. So what is different? I have a steam guage, but surely that cannot be it. I use it as per my check list whenever I am in landing or taking off phase, or switching tanks in flight. So I am not shy to use it.

Re: Boost Pump

Posted: Sat Mar 26, 2011 12:05 pm
by Gary
No problems with the pump in my 2003 DA40 with 1020 hours.

Re: Boost Pump

Posted: Sat Mar 26, 2011 1:18 pm
by Steve
Erik wrote:There seems to be some planes that go through lots of pumps faster than others, just from the anecdotal evidence I have seen on the two forums. My plane went 1600hrs before the first pump blew - and in real terms for a $1k pump even that is too much, but I am lucky compared to the several others who have had like Fred, many pumps blowing one after the other. I am not the only one to go well over a 1000hrs on my pump from either, as evidenced by reports some reports. So what is different? I have a steam guage, but surely that cannot be it. I use it as per my check list whenever I am in landing or taking off phase, or switching tanks in flight. So I am not shy to use it.
Only approximately 500 hours on my original pump, but nearly ten years of use. It would be interesting to get data regarding the failure mode(s). Is it a pump vane failure? An electrical failure (bad brushes, etc.)? Poor quality and bad design? Vibration due to inadequate mounting? Could be anything...

Steve

Re: Boost Pump

Posted: Sat Mar 26, 2011 1:32 pm
by Fred
Our Duke pump in the DA40 has 3 ground wires; unlike on a 172 that is very similar with 1 ground wire. I'm reaching here, but just maybe the additional grounds are each critical and although connected visually do not have a bonded ground working correctly....

I am looking into the new pump mentioned before that might address the failures. I have 3 DA40's on the field with me each a different model and all low time fuel pumps.

Two went for me under the 24 month warrenty. If those getting early failed pump had their AP/IA report them using a FAA SDR form. If it is a design issue the SDR's can help identify it and be used for corrective action.

Fred

Re: Boost Pump

Posted: Sat Mar 26, 2011 2:31 pm
by Rich
Fred wrote:Our Duke pump in the DA40 has 3 ground wires; unlike on a 172 that is very similar with 1 ground wire. I'm reaching here, but just maybe the additional grounds are each critical and although connected visually do not have a bonded ground working correctly....

I am looking into the new pump mentioned before that might address the failures. I have 3 DA40's on the field with me each a different model and all low time fuel pumps.

Two went for me under the 24 month warrenty. If those getting early failed pump had their AP/IA report them using a FAA SDR form. If it is a design issue the SDR's can help identify it and be used for corrective action.

Fred
The problem is in the electrical portion (at least it was in all mine). Commutator/brush wear was excessive. Dukes has theoretically taken corrective action, with changes to the internals of the pumps, as of pumps built last fall. If you have your overhauled it will be to the new "revision B" design. However, only time will tell whether this new revision will have reasonable life for more of us. There are a number of SDR's already filed, but Diamond and Dukes asks especially that we report rev-B failures to them so they can gain data.