What happened
The FAA’s narrative, in sentence case. The FAA writes it in capitals and removes private details.
The pilot in command of this Cessna 421 aircraft was receiving a CFR 135.297 flight check from an FAA inspector who was seated in the right seat of the aircraft (co-pilot's) position. They had landed on runway 14 at the Monmouth Executive Airport and was taxiing back to the runway for another take-off. While on the parallel taxiway, the observed a tractor mowing the grass between the taxiway and the runway. This is a non-tower airport and ther is no control over vehicles on the ramp or other areas of the airport's surface. The pilots were focused on the tractor in order to avoid a collision. While attempting to stay as FAR to the left side of this narrow taxiway as possible, the aircraft veered off the taxiway. While attempting to taxi back onto the taxiway, the left propeller sucked up loose gravel causing minor damage to the two blades on the left propeller.
As the FAA filed it
THE PILOT IN COMMAND OF THIS CESSNA 421 AIRCRAFT WAS RECEIVING A CFR 135.297 FLIGHT CHECK FROM AN FAA INSPECTOR WHO WAS SEATED IN THE RIGHT SEAT OF THE AIRCRAFT (CO-PILOT'S) POSITION. THEY HAD LANDED ON RUNWAY 14 AT THE MONMOUTH EXECUTIVE AIRPORT AND WAS TAXIING BACK TO THE RUNWAY FOR ANOTHER TAKE-OFF. WHILE ON THE PARALLEL TAXIWAY, THE OBSERVED A TRACTOR MOWING THE GRASS BETWEEN THE TAXIWAY AND THE RUNWAY. THIS IS A NON-TOWER AIRPORT AND THER IS NO CONTROL OVER VEHICLES ON THE RAMP OR OTHER AREAS OF THE AIRPORT'S SURFACE. THE PILOTS WERE FOCUSED ON THE TRACTOR IN ORDER TO AVOID A COLLISION. WHILE ATTEMPTING TO STAY AS FAR TO THE LEFT SIDE OF THIS NARROW TAXIWAY AS POSSIBLE, THE AIRCRAFT VEERED OFF THE TAXIWAY. WHILE ATTEMPTING TO TAXI BACK ONTO THE TAXIWAY, THE LEFT PROPELLER SUCKED UP LOOSE GRAVEL CAUSING MINOR DAMAGE TO THE TWO BLADES ON THE LEFT PROPELLER.