What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
Aircraft was being flown on first flight after maintenance. Pilot reported he had taken off from ffz bound for tus and had cleared the traffic pattern area. As he was attempting to contact phx for flight following his engine began to surge. He noted that the manifold pressure had dropped from 29-30 in map to aprox 17 in map. When phx ATC called him back he informed them that his engine was giving him problems. Since he was abeam iwa at the time he asked to be diverted to the nearest airport which was iwa for a precautionary landing. He also asked to be given the tower frequency as he did not have time to look the info up. Phx gave him iwa tower frequency and when he checked in iwa cleared him to land on rwy 30. The fire trucks were deployed and the pilot landed without further incident. While he was on base to final the engine regained power after surging several times and the pilot noted there was no further surging after that point.
The aircraft was able to taxi to parking on its own power and fire department determined there was no safety issues with the aircraft and departed.
The pilot contacted the maintenance facility that had performed work on the aircraft. The suggested that there might be water in the fuel as the aircraft had sat outside the night before and a rainstorm had moved thru the area. They suggested he drain the sumps and try running the engine again.
The pilot did remove several cups of fuel from the fuel sumps and he ran the engine up 2 times with no defects noted. He then decided that he would finish his flight home to ryan field as the day had warmed up considerably. He flew the aircraft to ryan and on several flights subsequent to the fuel flow issue and the engine has continued to run normally since.
As the FAA filed it
AIRCRAFT WAS BEING FLOWN ON FIRST FLIGHT AFTER MAINTENANCE. PILOT REPORTED HE HAD TAKEN OFF FROM FFZ BOUND FOR TUS AND HAD CLEARED THE TRAFFIC PATTERN AREA. AS HE WAS ATTEMPTING TO CONTACT PHX FOR FLIGHT FOLLOWING HIS ENGINE BEGAN TO SURGE. HE NOTED THAT THE MANIFOLD PRESSURE HAD DROPPED FROM 29-30 IN MAP TO APROX 17 IN MAP. WHEN PHX ATC CALLED HIM BACK HE INFORMED THEM THAT HIS ENGINE WAS GIVING HIM PROBLEMS. SINCE HE WAS ABEAM IWA AT THE TIME HE ASKED TO BE DIVERTED TO THE NEAREST AIRPORT WHICH WAS IWA FOR A PRECAUTIONARY LANDING. HE ALSO ASKED TO BE GIVEN THE TOWER FREQUENCY AS HE DID NOT HAVE TIME TO LOOK THE INFO UP. PHX GAVE HIM IWA TOWER FREQUENCY AND WHEN HE CHECKED IN IWA CLEARED HIM TO LAND ON RWY 30. THE FIRE TRUCKS WERE DEPLOYED AND THE PILOT LANDED WITHOUT FURTHER INCIDENT. WHILE HE WAS ON BASE TO FINAL THE ENGINE REGAINED POWER AFTER SURGING SEVERAL TIMES AND THE PILOT NOTED THERE WAS NO FURTHER SURGING AFTER THAT POINT.
THE AIRCRAFT WAS ABLE TO TAXI TO PARKING ON ITS OWN POWER AND FIRE DEPARTMENT DETERMINED THERE WAS NO SAFETY ISSUES WITH THE AIRCRAFT AND DEPARTED.
THE PILOT CONTACTED THE MAINTENANCE FACILITY THAT HAD PERFORMED WORK ON THE AIRCRAFT. THE SUGGESTED THAT THERE MIGHT BE WATER IN THE FUEL AS THE AIRCRAFT HAD SAT OUTSIDE THE NIGHT BEFORE AND A RAINSTORM HAD MOVED THRU THE AREA. THEY SUGGESTED HE DRAIN THE SUMPS AND TRY RUNNING THE ENGINE AGAIN.
THE PILOT DID REMOVE SEVERAL CUPS OF FUEL FROM THE FUEL SUMPS AND HE RAN THE ENGINE UP 2 TIMES WITH NO DEFECTS NOTED. HE THEN DECIDED THAT HE WOULD FINISH HIS FLIGHT HOME TO RYAN FIELD AS THE DAY HAD WARMED UP CONSIDERABLY. HE FLEW THE AIRCRAFT TO RYAN AND ON SEVERAL FLIGHTS SUBSEQUENT TO THE FUEL FLOW ISSUE AND THE ENGINE HAS CONTINUED TO RUN NORMALLY SINCE.