On April 10, 2011, about 1145 eastern daylight time, a Beech Model 99, N899AE, was substantially damaged during landing at Polk County Airport (4A4), Cedartown, Georgia. The airplane was registered to Aerodynamics Worldwide, Inc., and operated by Skydive Georgia, under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan was filed for the local sport-parachuting flight that departed 4A4 about 1110. In a telephone interview, the pilot explained that he was returning to 4A4 after deploying parachutists. He configured the airplane for landing, and only two of the three landing gear lamps illuminated when he lowered the landing gear. The pilot confirmed that he had an unsafe gear indication on the left main landing gear. He then actuated the test switch, and all three lamps illuminated, demonstrating that he did not have a burned-out indicating lamp. The pilot then retracted the landing gear, and attempted to lower it again. On this attempt, no lamps illuminated. He then lowered the gear manually, and again received an unsafe indication on the left main landing gear. While lowering the gear, he said the pressure required to pump the gear down became greater and greater until "something gave way." The pilot completed the landing on the nose and right main landing gear, which resulted in substantial damage to the left wing and fuselage. The pilot held a commercial pilot certificate with ratings for airplane single engine, multiengine, and instrument airplane. He held a flight instructor certificate with ratings for airplane single engine, multiengine, and instrument airplane. His most recent Federal Aviation Administration (FAA) second class medical certificate was issued March 16, 2011. The pilot reported 6,800 hours of total flight experience, of which 8 hours was in the accident airplane make and model. According to FAA records, an airworthiness certificate was issued for the airplane in 1968. The airplane had accrued 48,953 total aircraft hours. The most recent 100-hour inspection was completed February 14, 2011, at 48,945 total aircraft hours. Examination of the airplane at the scene by an FAA inspector revealed that the left main landing gear actuator displayed evidence of wear or failure where the drive entered the actuator housing. The floor access panel to the landing gear motor was removed, the manual landing gear extend feature was found engaged, and the circuit breaker for the motor was "popped." On June 21, 2011, the examination of the left landing gear actuator was supervised by the FAA inspector at 4A4. The overhauled actuator was installed on August 31, 2008, at 48,575 aircraft hours and 66518 cycles. The actuator accumulated 377.5 hours and 285 cycles since overhaul. Examination revealed that the supports for the actuator bearings lacked lubrication, and that the bearings also displayed wear due to inadequate lubrication. Due to the calendar months, aircraft hours, and cycles that had elapsed since the installation of the actuator, it could not be determined if the lubrication was inadequate at installation or if subsequent inspections failed to reveal a loss of lubrication (grease). According to the Hawker-Beechcraft Model 99 Series Maintenance Manual, a repetitive lubrication of the retract actuator and actuator support bearings at 1,000 cycles or 30 months (whichever occurs first) was prescribed. Additionally, Chapter 20-08-00 Standard Practices, page 201, included the following caution: "When washing the airplane with soap and water, use special care to avoid washing grease away from lubricated area. After washing the wheel well areas with solvent, lubricate all lubrication points. Premature wear of the lubricated surfaces may result if these precautions are not observed."