Date: 202106
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: Skyhawk 172/Cutlass 172
Operator: Personal
Operating under: Part 91
Flight plan: None
Mission: Training
Flight phase: Climb; Landing
Airspace: Class D ZZZ
ATC / advisory: Tower ZZZ
Aircraft component: Reciprocating Engine Assembly
Component problem: Malfunctioning
Reporter organization: Personal
Reporter function: Instructor; Pilot Flying
Reporter qualification: Flight Crew Instrument; Flight Crew Flight Instructor; Flight Crew Commercial
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy; Deviation / Discrepancy - Procedural FAR; Deviation / Discrepancy - Procedural Maintenance
Detector: Person Flight Crew
When detected: In-flight
Result: Air Traffic Control Provided Assistance; Flight Crew Requested ATC Assistance / Clarification; Flight Crew Landed in Emergency Condition; General Flight Cancelled / Delayed; General Maintenance Action
Contributing factors: Aircraft; Procedure
Primary problem: Aircraft

Narrative: Planned flight for the day was to ZZZ1 (for fuel) then to ZZZ. Preflight planning conducted with assistance from ForeFlight mobile application. Departed Runway XX. Climb to 1500 MSL; 14 min cruise to ZZZ1 with landing. Landed at ZZZ1. The flight was conducted satisfactorily. The aircraft was then fueled as necessary.Secondary preflight planning was completed. Satisfactory takeoff and climb out to 7;500 MSL. Approximately 29 minutes; started to notice engine roughness with a significant drop in tachometer RPM. The Pilot in command (PIC) took over as sole manipulator of control and emergency checklist for engine failure in flight initiated. Looked for suitable landing area. Increased in engine RPM occurred and became within glide distance of ZZZ. Engine roughness and drop in RPM began again and ZZZ Tower contacted; advising of need for precautionary landing due to engine roughness. Decision was made to not [get priority handling]. Smooth and satisfactory landing made at ZZZ. After slowing and attempting to turn off Runway; the aircraft did not have any right turning authority. Airplane would only turn left in circle when power applied. Suspected right tire or brake malfunction. Contacted the Tower and asked for permission to shut down aircraft on runway to inspect aircraft.Aircraft was satisfactorily shut down on Runway XY with airport crew arriving for assistance. On post flight walk around; it was found that the right tire became flat; no other external damage grossly observed. Also found to have fluid leak within right pilot side inside firewall. Aircraft was towed to FBO for diagnostics of engine and repair of right tire. When asked if needed to report anything to Tower or FAA; the ZZZ airport crew stated nothing was needed. Furthermore; the Tower did not mention of any need to provide any post flight report during communications. No accident or serious incident occurred.There were a few factors found on post-flight that may have caused the problems:1. Engine Roughness: The engine was new with approximately 28 hours on the engine. Engine during break in period was using Aeroshell 100W. Furthermore; this flight was conducted with cruise altitude at 7;500 MSL. Miscommunication and ill-information about any special procedures regarding aircraft break in were not discussed between aircraft owner and PIC. PIC was told to use 100W oil from previous aircraft owner (box in back of aircraft). Furthermore; the aircraft owner did not provide engine overhaul information or procedures needed for aircraft. On mechanic review; it was found that the left magneto was rotated 17 degrees causing the engine to overheat; an oil line by the firewall was damaged causing a leak; cylinders were glazed; induction air leak; and some crankcase oil leak. Overall a combination of these factors is what probably lead to engine roughness. Post flight testing; the engine performed within specifications 2250 static RPM; 600FPM climb; 2350 dynamic RPM. Engine oil consumption has increased; likely due to glazed cylinders; and is being sent to Company1 for re-honing. Furthermore; the magnetos are being sent in to [Company] Magneto to be re-checked.2. Right Flat Tire: No noted gross evident issues on pre-flight inspection for tires; struts; fairing; or braking systems. Landings was smooth and satisfactory. Theory for tire damage could be due to stuck break after landing and prior to right turn out to taxiway; in conjunction with weak spot on tire and/or a foreign object on runway and/or other. Tire was satisfactorily repaired at ZZZ. Reviewing this scenario there are a few factors to consider. There needs to be improved communication between aircraft owner and operator (PIC); especially during critical times where specific procedures are needed (such as a new engine break in). The right tire flat is a chance occurrence; and I do not think that the flight could have been handled different to prevent. The pilot did all in power to safely shut down the aircraft and immediately check out airplane to prevent any further damage.I have had a clean pilot record; commercial license and CFI. I will use the lessons from this flight for myself and all future students for the purpose of discussing complete airplane maintenance with airplane owners (especially new airplanes); what to do when engine becomes rough; and procedures to follow with a flat tire.




Synopsis: Instructor reported engine roughness and loss of power resulted in a precautionary landing at destination airport.