Flight Crew Instrument; Flight Crew Private
Flight Crew Last 90 Days 33.6; Flight Crew Total 136.6
Human-Machine Interface; Situational Awareness
Aircraft Equipment Problem Critical
Flight Crew Landed in Emergency Condition; Flight Crew Returned To Departure Airport; General Maintenance Action
Aircraft
The purpose of the flight was IFR training.  I was the safety pilot for the flight; this flight was to be done under VFR and flight following.  Once we were established in the cruise portion of the flight; we decided to contact Center for flight following; and radar services were established.  A few minutes passed and the Controller came back on frequency to announce our Mode-C transponder was not coming through and asked us to recycle and report our present altitude.  I responded to the request but the Controller never acknowledged and repeated his request.  We tried to responded but it seemed we had lost the ability to transmit.  We proceeded to squawk 7600 and decided to turn back.  Shortly thereafter we realized that our entire electrical system was becoming inoperative.  It was getting quite dark and we were unable to turn the pilot controlled lighting on at the airport or have our own aircraft lighting on.  As a flight crew we decided to have the other pilot fly the aircraft and prepare for the no-flap landing.  I continued to try the radios (we were still receiving very limited electrical power) and to scan for other traffic.  We continued toward the airport; I did not see any other traffic in the vicinity of the airport and we elected to land on Runway 27; the shorter runway but more favorable with the winds.  We entered the left downwind of the runway and proceeded to land with no light or flaps without further incident.  Once on the ground I proceeded to call the ARTCC and informed them of our situation and why we could not communicate with them and to cancel our flight following.  This was our first major incident in our flying careers.  Once on the ground I realized we did not run through the emergency checklist.  The ammeter neither showed a charge or a discharge of the battery; so we assumed it was a faulty wiring or a short in the system; since before the flight the landing light was replaced.  Throughout the flight I felt we maintained good situational awareness and had good crew resource management.  We never became flustered and had a cool head.  Positive control of the aircraft was maintained throughout the flight.
C172 safety pilot describes the loss of electrical power during a VFR instrument training flight using flight following.  The two pilots return to their departure airport without exterior lighting and land flaps up on an unlighted runway.