Trogdor
Pre-takeoff checklist
I had an issue on Friday that had me abort a take-off: The aux fuel pump in a 1978 PA28B (Dakota) with an O540 died. I discovered this post abort and the Club I fly with has since ordered a new one. However, I am concerned still about the mechanical driven fuel pump because….
The reason for the abort was the fuel pressure gauge under the G3X EIS page went red during my roll out. I was still accelerating on the ground but it dipped into the red. Yes, I had the aux fuel pump switch on but presumably it was inop already. Apparently, it had died before take-off and I didn’t notice! That’s on me and I need to verify the pressure number before letting the throttle rip (I thought I did but I’m not 100% sure now, I do verify it during my run-up but I realize there is a short window where yeah, it could die the next time I tap it on). I will fix a few things in the way I do checklists and callouts to close this gap.
But regardless, shouldn’t the mechanical one still hold enough pressure in the lines even if the aux dies? i.e. I understand the issue with low-wing aircraft and gravity but I was always of the belief that an aux fuel pump was a “just in case” not “if you don’t hit this switch the end” kind of thing. I could very well be wrong. The engine btw was humming along when I aborted so it didn’t feel like it was starving (gph was around 20ish if I recall but I will have to look at logs). I did have full tanks when it happened.
Trust me in that I am very relieved that gauge went red and I avoided potentially a very, VERY bad day. But I am wondering if we should be looking at that mechanical pump and/or sensor as well.
NOTE: In a semi-related note, the fuel pressure gauge has gone red on climb out if I turn off the fuel pump. We were told that Piper’s typically run low because of the sensor’s placement and it being carberated (0.5 psi is considered nominal but I have seen it dip to 0.1 or 0.2 despite the gph still high).
The reason for the abort was the fuel pressure gauge under the G3X EIS page went red during my roll out. I was still accelerating on the ground but it dipped into the red. Yes, I had the aux fuel pump switch on but presumably it was inop already. Apparently, it had died before take-off and I didn’t notice! That’s on me and I need to verify the pressure number before letting the throttle rip (I thought I did but I’m not 100% sure now, I do verify it during my run-up but I realize there is a short window where yeah, it could die the next time I tap it on). I will fix a few things in the way I do checklists and callouts to close this gap.
But regardless, shouldn’t the mechanical one still hold enough pressure in the lines even if the aux dies? i.e. I understand the issue with low-wing aircraft and gravity but I was always of the belief that an aux fuel pump was a “just in case” not “if you don’t hit this switch the end” kind of thing. I could very well be wrong. The engine btw was humming along when I aborted so it didn’t feel like it was starving (gph was around 20ish if I recall but I will have to look at logs). I did have full tanks when it happened.
Trust me in that I am very relieved that gauge went red and I avoided potentially a very, VERY bad day. But I am wondering if we should be looking at that mechanical pump and/or sensor as well.
NOTE: In a semi-related note, the fuel pressure gauge has gone red on climb out if I turn off the fuel pump. We were told that Piper’s typically run low because of the sensor’s placement and it being carberated (0.5 psi is considered nominal but I have seen it dip to 0.1 or 0.2 despite the gph still high).
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