NTSB Factual Report

On November 14, 2007 at 1820 central standard time, an Aero Commander GA-500-B, N444CB, operated by Central Air Southwest, sustained substantial damage when it experienced a gear collapse upon landing on runway 01 (7,002 feet by 150 feet, concrete) at Charles B. Wheeler Downtown Airport (MKC) in Kansas City, Missouri. The commercial pilot was not injured. The 14 Code of Federal Regulations Part 135 cargo flight departed Cahokia Municipal Airport (CPS), Cahokia, Illinois, for MKC at 1630 local time. Visual meteorological conditions prevailed at the time of the accident and the flight was on an instrument flight rules (IFR) flight plan.

The pilot reported that he performed the landing checklist while he was on a visual approach following jet traffic to runway 01. He lowered the landing gear and flaps, and confirmed that the three green lights illuminated, which indicated that the landing gear were down. He reported that the landing and flair were normal. He reported that he felt the main landing gear touch down on the runway. When the nose gear touched the runway he applied brake pressure. He was preparing to taxi off on Delta taxiway when he heard some loud noises. He reported that the "main landing gear collapsed and I could no longer maintain centerline of the runway." The pilot reported that the distance between where the main gear collapsed and the belly of the airplane started to skid on the ground to where the airplane stopped was about 270 feet.

The chief pilot of Central Air Southwest reported that he arrived at the scene of the accident about 1845 to assist with removing the airplane from the runway. The airplane was found with the left and right main landing gear folded back with the wheels canted sideways and resting on the runway. (The main landing gear rotate 90-degrees when they are retracted so they can lie flat in the nacelle wheel wells.) The nose gear was in the down position. The chief pilot verified that the landing gear handle was in the down and locked position. He reported that when he turned the master on, the nose gear down lock light was on and the left and right main gear lock lights were not on. The airplane was raised up using a forklift and aircraft jacks. The chief pilot reported that when the main landing gear were free of the runway, both main landing gear locked in place in the down position. When the airplane was lowered onto its main landing gear, the two main landing gear lights illuminated. The propellers had not struck the runway during the accident, so the engines were started and the airplane was taxied back to the operator's hangar. The inspection of the airplane revealed that there was damage to the airplane's belly stringers and formers that required them to be replaced.

An inspector from the Federal Aviation Administration visually inspected the airplane's landing gear. The inspection revealed that one of four clevises were broken where the landing gear actuator attached to the trunion, but there was no evidence that the airplane's main landing gear lock down mechanism had failed on either the left or right main landing gear.

A review of the aircraft maintenance records indicated that the last 125-hour inspection under the Approved Aircraft Inspection Program (AAIP) was conducted on October 25, 2007. The main landing gear and the nose landing gear were inspected as part of the 125-hour inspection. A gear retraction test was also conducted during the inspection. The airplane had flown about 67 hours since the inspection.

Two rubber bungee shock cords on each main landing gear assist in forcing the drag brace linkage over center to form a positive lock when the gear is extended. The maintenance records indicated that the left and right landing gear bungee shock cords were replaced on April 19, 2007.

The operator reported that the airplane was not operated since the accident on November 14, 2007, due to lack of parts, and the operator removed the airplane's engines to be used on other airplanes. The operator reported that no maintenance had been performed on either landing gear. The operator reported that an operational check of the landing gear was conducted in accordance with the 500B Maintenance Manual on February 8, 2008, and the landing gear were found to be operational.

NTSB Probable Cause

The pilot delayed lowering the landing gear in the landing sequence and the main gear were not in the down and locked position upon touchdown.