On September 26, 2017, at 1638 Pacific daylight time, a Piper PA-24-260 airplane, N9020P, sustained substantial damage during landing at Whiteman Airport, Los Angeles, California. The private pilot was not injured. The airplane was registered to and operated by the pilot as a Title 14 Code of Federal Regulations Part 91 personal flight. Visual meteorological conditions prevailed at the time of the accident and no flight plan had been filed for the flight which departed from Camarillo, California about 1600. The pilot reported that he lowered the landing gear while preparing to land on runway 12. He stated that after lowering the gear, he felt the airplane's drag increase but could not remember if he got a confirmation they were down and locked from the indicator light. He further stated the landing flare was normal and the airplane touched down on the main landing gear. Thereafter, the nose gear settled toward the runway and as the airplane continued on the landing roll, all three gear collapsed. The airplane incurred structural damage to the fuselage. A Federal Aviation Administration certified mechanic examined the airplane after the accident. He stated that all three landing gear were in the gear wells. The main landing gear doors were not damaged and only the nose landing gear door had light scratches, which he thought was consistent with the landing gear being retracted at the time of impact. After recovering the airplane, the mechanic swung the landing gear and performed an examination. He found no mechanical malfunctions or failures that would have prevented normal operation.