Date: 201208
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Weather elements / visibility: 25
Light: Daylight
Aircraft: Skyhawk 172/Cutlass 172
Operator: Personal
Operating under: Part 91
Flight plan: None
Mission: Training
Flight phase: Landing
Airspace: Class D ZZZ
ATC / advisory: Tower ZZZ
Aircraft component: Manifold Pressure Indication
Component problem: Malfunctioning
Reporter organization: Personal
Reporter function: Instructor; Pilot Not Flying
Reporter qualification: Flight Crew Instrument; Flight Crew Flight Instructor; Flight Crew Commercial; Flight Crew Multiengine; Maintenance Powerplant; Maintenance Airframe
Human factors: Situational Awareness; Physiological - Other; Distraction; Communication Breakdown
Second reporter function: Trainee; Pilot Flying
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Ground Event / Encounter Ground Strike - Aircraft
Detector: Person Flight Crew
When detected: In-flight
Result: Aircraft Aircraft Damaged; Flight Crew Took Evasive Action; General Maintenance Action
Contributing factors: Human Factors; Aircraft
Primary problem: Human Factors

Narrative: Student and I were performing touch and goes. On the upwind of a touch and go we noticed that the manifold pressure gauge was reading atmospheric pressure no matter the throttle position. The engine was still performing normally but we decided to make the next landing a full stop. I took the controls momentarily on the start of the downwind so that the student could tap the gauge. We exchanged controls again and requested a full stop. We were performing short approaches and got clearance for another short approach. The student reduced throttle (the manifold gauge still read atmospheric pressure) and selected flaps to 20 degrees. We touched down gear up on 28L; which is the runway we were cleared for; the student added power and I took controls and put the gear down. As I climbed out; Tower was notified immediately by an aircraft in the runup area for 28L of what had just occurred. Tower asked if we needed any assistance. The plane was flying normally so we declined; obtained a clearance to land and flew the pattern. I flew the aircraft; performed a soft field landing and taxied back. Upon shut down it was revealed that the prop did strike the ground. There were several human factors involved. I; the instructor; have been teaching now for just over three years with over 1;000 hours of dual given time. I can say that I have become complacent in my teaching at times which has degraded my once prided professional manner with which I taught. Also; I have had a lot going on at home with a new baby as well as being the sole provider for my family has put some additional stress on me. I have also been very busy with other personal and professional obligations which have stretched my attention and energy. I failed to verify that the gear was down with my own BGUMPS checklist. I also relied on the aircraft too much to warn us that the gear was down but due to the fact that the manifold pressure was at atmospheric level and the flaps were only at 20 the horn did not go off. The cause of the prop strike was lack of checklist usage; lack of communication during the exchange of controls of the state of the aircraft; fixation on the inoperative instrument; complacency by me; and failure to verify that the gear was down. Re-currency training of both flight and ground as well as being aware of a complacent mindset can be used to prevent this from happening in the future. Also; we should have notified Tower of the manifold pressure situation. It might have slowed us down in the cockpit as well as drawn attention to us by the Tower who may have notified us that our gear was still up.


Second narrative: When I was at my point to land I began my flare. I realized that the wheels had not touched down yet and figured I must be too high so I continued to flare. When we struck the runway I went full power to go around and my instructor took the controls from me.


Synopsis: An instructor pilot and his student reacted quickly and initiated a rejected landing and go around when their C-172RG touched down lightly on its belly with the nose high. A safe landing followed after which they learned that they had suffered a prop strike during the event. A contributing factor was an apparently failed manifold pressure gauge which distracted both pilots from checklist SOPs.