NTSB Factual Report

On September 19, 2014, at 1030 central daylight time, N115DD, a Robinson R-22 Beta helicopter, landed hard during a forced landing near the St.Louis Downtown Airport (CPS), Cahokia, Illinois. The commercial rated pilot was not injured. The helicopter was registered to a private corporation and operated by the pilot. No flight plan was filed for the local flight that originated at CPS about 1000.Visual meteorological conditions prevailed for the personal flight that was conducted under the provisions of 14 Code of Federal Aviation Regulations Part 91.

The pilot stated that shortly after takeoff the clutch warning light came on. He did not think this was abnormal because the belts would heat up and re-tension themselves causing the light to briefly illuminate. However, as a precaution, and as directed by the manufacturer, he waited to see if the light would go out in 10 seconds. The light did not turn off, so he pulled the clutch circuit breaker and landed immediately in a parking lot. After landing, the pilot locked the controls, got out of the helicopter and looked inside the engine compartment. He did not see anything abnormal. At this point, the pilot said a group of young men, who "didn't look friendly" were waving their arms and saying that he wasn't allowed to land there. The pilot was unable to find his cell phone to call for help, so he elected to get back in the helicopter and make the short flight back to the airport. The pilot then departed and was about 500 yards from landing on runway 5, when the helicopter began to vibrate and "make a lot of noise." The pilot entered an autorotation. He said, "As I slowed and did the flair to land the helicopter yawed to the left as I pulled collective to run it on. I realized there was no tail rotor. The skids contacted the ground and dug into the soft ground. I think that's when the tail boom lifted and the blade cut it off." The pilot said that the accident could have been prevented if he had turned back and landed at the airport after the clutch warning light illuminated. He also told an FAA inspector that he "screwed up" and should not have take off after the caution light came on.

According to the Robinson R22 Pilot's Operating Handbook, page 3-9, its states that when the clutch warning light illuminates, the clutch actuator is on, either engaging or disengaging. When the switch is in the ENGAGE position, the light stays on until the belts are properly tensioned. Never take off before the light goes out. It also says, "Clutch light may come on momentarily during run-up or during flight to retension belts as they warm-up and stretch slightly. This is normal. If, however, the light flickers or comes on in flight and does not go out within 10 seconds, pull CLUTCH circuit breaker and land as soon as practical. Reduce power and land immediately if there are other indications of drive system failure (be prepared to enter autorotation)."

A postaccident examination of the helicopter was conducted by the Federal Aviation Administration (FAA) with the assistance of the helicopter manufacturer and the mechanic that performed the last annual inspection, which was conducted on August 30, 2014. The helicopter had only accrued 9.1 hours since the inspection. According to an FAA inspector, the fan assembly had sustained extensive damage and the bolts that secured the fan puller were loose. It appeared that the head of one of the bolts was extensively worn away and had rubbed against the lower actuator bearing. The mechanic told the FAA that "they" may have "messed up" and may not have properly tightened the bolts during the annual inspection. The fan assembly was then removed, which exposed the lower sheave and lower actuator bearing (Part No. A181-4). There was no evidence of grease and the bearing exhibited extensive damage.

The fan assembly, fan shaft, lower actuator bearing and clutch actuator were sent to the NTSB's materials laboratory for further examination to determine what caused the fan assembly to fail. The forward face of the fan wheel and some of the fan wheel airfoils exhibited circumferential scrape marks. The inner diameter of the fan wheel had galling damage and discoloration from heat tinting. Some denting was observed on the edges of the fan wheel out diameter. The fan shaft had mated to the inner diameter of the fan wheel and was discolored from heat tinting, and there were scrape marks around the outer diameter. The fan shaft was severely distorted and had thinning of the shaft diameter. The lower support bearing assembly exhibited scoring on one of the faces and a portion of one side was separated. Disassembly of the lower support bearing revealed most of the rollers were deformed and some were flattened and melted. The race on the inner ring had galling and circumferential scrape marks. The inner diameter of the inner ring was also heat damaged and deformed. The bearing cage was deformed and had separated into multiple pieces. One side of the lower bearing support housing was deformed along the outer edge. The mating ring still pressed inside the housing had smeared material on the race on the area of the deformed housing. The deformation and extensive heat damage observed on these components was consistent with a lack of lubrication and not a loose bolt.

A review of the engine maintenance logbook revealed that the mechanic, who performed the last annual inspection, made a certified entry that he lubricated the lower actuator bearing.

NTSB Probable Cause

The pilot’s poor decision to take off with the clutch warning light illuminated, which resulted in the total failure of the fan assembly due to a lack of lubrication. Contributing to the accident was the mechanic’s failure to lubricate the lower actuator bearing at the last annual inspection.