Flight and Incident
A certified flight instructor (CFI) and a private-rated student pilot departed on an instructional cross-country flight under instrument flight rules (IFR) with an inoperative vacuum pump. While en route to their planned destination, the pilots encountered a snow shower and diverted towards Altoona, Pennsylvania. Shortly after the diversion, the engine began to surge and lose power.
Engine and Landing Attempt
The CFI applied carburetor heat, which provided a momentary restoration of engine power. However, the engine lost power again, and the airplane subsequently crashed in a densely wooded area at night.
Post-Accident Examination
Examination of the wreckage revealed that the right fuel tank was empty, while the left fuel tank was over three-quarters full. The fuel selector was found in the right tank position.