Went up for flight this morning and ran into something new. I was in level flight at 60% power, mixture running at peak EGT or slightly below and I had a series of 3 short low fuel pressure events. Pressure dropped below 10 for 2 seconds, I could hear it in the engine sound, I got an aural alert from my Skyview EMS and I saw the fuel pressure gauge drop. Each event lasted about 5 seconds where pressure was below the normal 25 and they all resolved themselves. I responded to the first one by turning on the boost pump and pushing in the mixture all the way. The second event followed 30 seconds later and the last event a little more than a minute later. Fuel flow stayed steady through each event (corresponding with the state of the boost pump and mixture at the time) and I didn't see much change in the RPM although I'm on a C/S prop. After the third event I switched back to my left tank - I'd been on the right tank since about 5 minutes earlier. I didn't have any issues on the left tank and immediately returned to land. I did switch back to my right tank after landing and did an uneventful runup prior to shutting down.
I feel good about how I responded to the hiccups, I reacted quickly with the boost pump and mixture and was running through my immediate options including a precautionary landing at the small airport I had overflown a few minutes earlier. I had plenty of altitude, about 3500' AGL and I would have had about 4 minutes to get it down should the engine have quit.
My question for the brain trust here is this. Is this a highly unusual and concerning issue? I don't know what caused the stumbles, fuel contamination? air pocket? My data logs are pretty thorough, is there any other counter that would give a clue about the cause? I'm a little reluctant to go back out without some idea about what happened.
At least I found out that my autopilot works well as was the purpose of my flight today.
I feel good about how I responded to the hiccups, I reacted quickly with the boost pump and mixture and was running through my immediate options including a precautionary landing at the small airport I had overflown a few minutes earlier. I had plenty of altitude, about 3500' AGL and I would have had about 4 minutes to get it down should the engine have quit.
My question for the brain trust here is this. Is this a highly unusual and concerning issue? I don't know what caused the stumbles, fuel contamination? air pocket? My data logs are pretty thorough, is there any other counter that would give a clue about the cause? I'm a little reluctant to go back out without some idea about what happened.
At least I found out that my autopilot works well as was the purpose of my flight today.