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While on my instrument checkride this week (I passed!) I experienced a boost pump failure. The circuit breaker popped as soon as I applied full power, according to my examiner. What followed was some confusion (he said, "oh, look, your fuel pump breaker popped" sometime after takeoff when I'd already flipped the fuel pump switch off, and I assumed this was his crooked way of simulating an in-flight equipment failure... Only after my next landing did we figure out that he meant this was a real failure). We agreed to continue the checkride without the pump, and finished it an hour later. I parked by his office, and then later got the plane started to move it to it's usual spot.

But now I'm worried -- I have an appointment to have a Diamond certified center check and fix the (likely expired, at 700 hrs) pump, but it's at another airport. If does anyone have any advice on starting the airplane without the boost pump priming? I might luck out again and have it start with whatever remaining fuel in the lines, or I might not... and it would be great to have a pumpless start procedure in that case.

A cold start without the boost pump will probably require more cranking. I might suggest cranking with not only full mixture but full throttle for a few seconds to help increase fuel flow while cranking, but only briefly.

A (true) parable. In 1983 a friend of mine took off in and totaled my Cherokee 140. In that case the backup fuel pump wasn't working. But it wasn't strictly speaking a boost pump, as this was a carburetor engine (O-360). The wreck had nothing to do with the pump not working (density altitude). But the NTSB (or FAA, don't recall which right now) did slap his hand (no suspension or anything) for taking off with inoperative required equipment.

Ilya,

Congrats on your IPC ride. Well done!

May I ask how many hours you have on your plane, and whether it is the OEM pump? Mine failed last year before a flight so I did not try to start it at all. I don't know if it is possible to start without and I would be very cautious abour burning out a starter. No harm in trying, but be careful you don't crank too long. My .25.

L

Lou, thanks. I've got a bit more than 100 hrs on the plane, and the plane itself has ~2,700 tach. Now that I take a closer look at the logs, what I thought was a fuel pump replacement was likely the mechanical pump being changed (Lycoming part number and all). The last entry for the electric pump seems to be slightly over 1,000 hours ago and with a Weldon part number. I guess that speaks well for Weldon pumps?

Interesting. May I ask the Weldon part number? I am curious if this is the old style with the plastic impeller or the new one with the metal impeller. Also, was it making a noise before failure?

There are some really informative topics on the boost pump in this forum, btw. You may find something useful there.

Haykinson....If you don’t mind I’m going to slightly Segway this topic...how many of you turn the elec pump off after your prime and start the engine without the electric pump on? I was taught this contrary to POH, and the motor seems to start the all the same both ways.

Roxi5m9 wrote:Haykinson....If you don’t mind I’m going to slightly Segway this topic...how many of you turn the elec pump off after your prime and start the engine without the electric pump on? I was taught this contrary to POH, and the motor seems to start the all the same both ways.

I do. For cold starts I just run it for a 5-count, full rich and full throttle. Then turn it off and bring the throttle back to a reasonable spot. For hot starts not at all.

Same.

Lou wrote:Interesting. May I ask the Weldon part number? I am curious if this is the old style with the plastic impeller or the new one with the metal impeller. Also, was it making a noise before failure?

Logs say part number 18002-B.

As for noise -- can't tell. My process is to use it for priming (count to 5 or 6, and then turn it off), and to then only turn it on for takeoff and landing. It certainly sounded ok to me during priming; in the few seconds between turning it on and it failing during takeoff I couldn't possibly say whether there were any odd noises.

A popped breaker isn't a failure mode I can recall hearing about before. This implies a short in the wiring or the pump itself, or a locked rotor.