Musketeer 23
Maintenance Airframe; Maintenance Powerplant; Maintenance Inspection Authority
Maintenance Avionics 15; Maintenance Inspector 10; Maintenance Lead Technician 10; Maintenance Technician 10
Situational Awareness; Troubleshooting
Aircraft Equipment Problem Less Severe
Flight Crew Landed As Precaution
Aircraft; Procedure; Incorrect / Not Installed / Unavailable Part; Human Factors
Annual inspection was performed; item on annual checklist was to perform inspection of fuel gas-collator filter screen- inspection was complied with and no issues noted. I had personally flown the aircraft several times prior taking it for new owner delivery. After descending down from 7;500 ft. to 3;500 ft. I noticed the engine was running rough. RPM was low for cruise power setting and unable to get more than 2000 RPM. [I] decided to land aircraft immediately at ZZZ.Maintenance on field discovered that one fuel nozzle was plugged. [They] cleaned fuel nozzle and replaced fuel supply line to the injector. Ops checked engine and it was all satisfactory. I insisted that we look into right fuel tank for contamination- no debris found. Later Maintenance performed another engine run and discovered that engine is running rough again. Continued with troubleshooting and discovered that screen element installed in fuel gas-collator was not the correct screen. I advised them to install new screen. They suspected unapproved filter screen installed. I did last annual on airplane and screen check. There was no way for me to know that the screen was not aircraft approved or type approved.
Aircraft Technician reported wrong fuel filter was installed.