A certificated flight instructor, who witnessed the landing sequence, reported that upon touchdown, the airplane porpoised three times. He reported that the pilot aborted the landing, the airplane climbed to approximately 50 feet above ground level, and then the airplane landed on the remaining runway without further incident. The Federal Aviation Administration aviation safety inspector, who spoke with the pilot, stated that the pilot reported that the airplane was "not stable" during the approach and that he should have aborted the landing. The pilot also reported that the crosswind condition "complicated his final approach," which was "too high." The airplane landed hard, resulting in substantial damage to the firewall. The pilot did not make a statement to the National Transportation Safety Board (NTSB) investigator-in-charge during a telephone interview. The pilot did submit a NTSB Form 6120.1 Pilot/Operator Aircraft Accident/Incident Report, but with no narrative of the accident. The pilot did not report any pre-impact mechanical failures or malfunctions with the airframe or engine that would have precluded normal operation.