Small Aircraft; Low Wing; 2 Eng; Retractable Gear
Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Flight Instructor
Flight Crew Last 90 Days 150; Flight Crew Total 5200; Flight Crew Type 100
Confusion; Situational Awareness
Ground Event / Encounter Ground Strike - Aircraft
Aircraft Aircraft Damaged; Flight Crew Became Reoriented; General Evacuated
Airport; Human Factors
While taxiing to obtain fuel on a night IFR cross country flight; we had a prop strike. It happened on the south side of a refueling station (the 'mushroom') that had a 100LL sign; which was the type of fuel we were looking for. As we slowly taxied to the refueling station we were turning left to align the airplane with the refueling station fuel hose reels; the starboard main landing gear went down an unmarked drain hole with a metal grate on the bottom [at which time the prop strike occurred]. After shutting off both engines; we disembarked and only then realized the refueling station was for fuel trucks. The refueling station had previously been available for airplanes. There was no signage to indicate for fuel trucks only and not for airplanes.
The instructor pilot aboard a small twin engine airplane taxied to what he believed to be the aircraft refueling station at HIO and; only after taxiing into a depressed drainage grate and striking the right prop; learned it was intended solely to refuel gas trucks which conducted aircraft refueling on the adjacent ramp.