What happened
The pilot was conducting a visual flight rules (VFR) on-top arrival when cleared for radar vectors toward a non-directional beacon (NDB) approach. During the descent through the cloud layer, which lasted approximately five to eight minutes, the aircraft encountered icing conditions. Approximately one-half mile from the runway on final approach, the pilot noticed the nose becoming progressively heavy and observed an airspeed indication of 90 knots. A go-around was initiated; however, while airspeed increased to 92 knots, the nose pitched further down. The aircraft subsequently touched down hard on the nosewheel first, bounced off the runway surface, and struck the pavement again. The nosewheel collapsed during this sequence, bringing the aircraft to a stop just off the runway.
The investigation
Post-acc examination revealed approximately one-eighth inch of ice accumulation on the leading edges of the wings. An inspection of the flight controls confirmed no mechanical issues were present. The pilot reported that the pitot tube heater was slow to warm up after the incident and believed ice had accumulated on the pitot head, causing erroneous airspeed readings.
Findings
The aircraft acted as if it were flying at only 75 to 80 knots during the final touchdown phase due to the inaccurate airspeed indication caused by pitot tube icing. This led to an excessive descent rate and a hard landing that resulted in nosewheel collapse.