Skyhawk 172/Cutlass 172
Flight Crew Multiengine; Flight Crew Commercial; Flight Crew Flight Instructor; Flight Crew Instrument
Flight Crew Last 90 Days 150; Flight Crew Total 415; Flight Crew Type 290
Aircraft Equipment Problem Critical
Flight Crew Landed in Emergency Condition
Aircraft
I did a preflight inspection on the aircraft. I sumped all three sump tanks and there was no sign of water. I also did not know if the fuel gauges were reading correctly; so I did a manual fuel inspection and found the fuel sufficient to having about 12 to 15 gallons in the 85 gallon tanks. At a max fuel burn of 8 GPH; I calculated a total flight time of 1hour and 30min. I was doing a sales demo flight which was to last a total of 15 min to show the good working conditions of the aircraft. After the preflight inspection the plane showed to be in good airworthy condition. I met with the clients who were looking into the aircraft to teach one of them to fly. I informed them that I was going to do another walk around and then we can load and taxi out. After I started the engine; I received the local ATIS and corrected the altimeter reader and adjusted my directional gyro to the correct heading.  I taxied out checking all engine systems and they looked in good working order. I pulled off to the side of the taxi area to do a run up; with checklist. The systems were in good working order; so I then called Tower and advised; 'Run up complete; holding short [Runway] XX.' Tower responded; 'Clear for departure XX on course approved.'I added 10 degrees of flaps power and allowed the airspeed to come alive once I saw a engine instrument in good order; I added full power. The plane rapidly increased and at 55 Vr I rotated. Now at midfield I had some engine noise as if it was getting too much fuel. I reached the mixture and reduced the mixture. The engine then sounded like normal and airspeed increased to 75 knots. I continued my climb out and at the approach end of [Runway] XX the power seem to cut out with no usable runway. I feathered the throttle and could see that the engine was still getting power but the manifold pressure was at 15. I saw the lake straight ahead and the road up under me. Knowing that I had some engine power left; I made a 40 degree [turn] back east to plan to land on the [nearby] four lane road. Looking ahead; I saw power lines approaching and made the choice not to add any additional flaps go the wheels down before power lines. The engine was still running at the time and I called Tower to let them know that we did not need medical. I taxied the aircraft around to the side of the road and checked on passengers. I shut down the engine; unloaded the passengers; and pushed the aircraft off the main road. I inspected for damage. No damage on the aircraft and none to passengers.
An instructor pilot demonstrating a C172 for a potential buyer suffered a loss of power after takeoff and landed safely on a road adjacent to the airport.