NTSB Final Report: Hollywood, FL

Analysis

The instructor reported hearing a popping and banging sound while hover-taxiing during an instructional flight followed by an uncommanded right yaw. The instructor attempted to regain control, but the helicopter collided with the ground and rolled over onto its right side.

Postaccident examination of the helicopter revealed that the tail rotor gearbox had fractured and that the tail rotor assembly had separated from the helicopter. Additional examination of the tail rotor blades, which had remained attached to the tail rotor drive shaft and gearbox, revealed corrosion and interior delamination of the blades. There was also erosion present on the blade leading edges, which likely provided a path for moisture to ingress, thereby resulting in the observed corrosion as well the failure of the bonding adhesive within the blade. It is likely that this condition resulted in an imbalance of the blades that imparted a vibratory loading onto the tail rotor gearbox that ultimately resulted in its failure during the accident flight. Review of partial maintenance records provided by the operator revealed that the tail rotor blades installed on the accident helicopter were not the blades that were noted in the maintenance logbooks, and the service history of the installed blades could not be determined.

Probable Cause and Findings

The National Transportation Safety Board determines the probable cause(s) of this accident to be: Inadequate maintenance of the helicopter’s tail rotor blades, which resulted in a failure of the tail rotor drive system, and an inflight loss of yaw control from which the flight instructor was unable to recover.

Findings

Aircraft                                         Tail rotor blade - Failure

Personnel issues                        Scheduled/routine inspection - Maintenance personnel

Factual Information

History of Flight

Maneuvering-hover                     Flight control sys malf/fail (Defining event)

Uncontrolled descent                  Collision with terr/obj (non-CFIT)

On July 27, 2022, about 1345 eastern daylight time, a Robinson R22 helicopter, N42WC, was substantially damaged when it was involved in an accident near Hollywood, Florida. The flight instructor was not injured, and the student pilot received minor injuries. The helicopter was operated as a Title 14 Code of Federal Regulations Part 91 instructional flight.

According to the instructor, after completing an engine run-up, he “picked up” the helicopter and was air-taxiing to the practice area to conduct some hover work. Before reaching the practice area, a “popping” and “banging” sound was heard from behind the helicopter, followed by an uncommanded right yaw. The instructor attempted to regain control, but the helicopter collided with the ground and rolled over onto its right side. The instructor and student pilot exited the helicopter.

Examination of the helicopter by a Federal Aviation Administration inspector revealed that the tail rotor assembly was separated; both tail rotor blades remained attached and the output shaft was also attached. Both tail rotor blades were bent and were impact damaged. The tail rotor gearbox was fractured, with half of the casing missing. The main rotor blades were bent down and curled, with multiple kinks and creasing from leading edge to trailing edge. Multiple impact signatures were noted on the ground within the rotor diameter of the helicopter.

Examination of the tail rotor gear box and tail rotor blades revealed corrosion within both blades. The exam revealed that erosion of the leading edge provided a path for moisture to ingress into the bond joint and deteriorate the adhesive.

The owner and the mechanic stated that the helicopter’s maintenance records were previously damaged by water and had to be reconstructed digitally. The records provided appeared to show that most life-limited parts had been overflown by 374.1 hours. The pilot stated that he had noted damage on the helicopter’s tail rotor blades during a preflight inspection about two weeks before the accident and that the operator had replaced the blades. Review of the available maintenance records for the helicopter revealed that the serial numbers of the tail rotor blades installed did not match that noted in the maintenance records. The available records also did not document any replacement of the tail rotor blades.

Flight instructor Information

Student pilot Information

Aircraft and Owner/Operator Information

Meteorological Information and Flight Plan

Airport Information

Wreckage and Impact Information

Administrative Information

The National Transportation Safety Board (NTSB) is an independent federal agency charged by Congress with investigating every civil aviation accident in the United States and significant events in other modes of transportation— railroad, transit, highway, marine, pipeline, and commercial space. We determine the probable causes of the accidents and events we investigate, and issue safety recommendations aimed at preventing future occurrences. In addition, we conduct transportation safety research studies and offer information and other assistance to family members and survivors for each accident or event we investigate. We also serve as the appellate authority for enforcement actions involving aviation and mariner certificates issued by the Federal Aviation Administration (FAA) and US Coast Guard, and we adjudicate appeals of civil penalty actions taken by the FAA.

The NTSB does not assign fault or blame for an accident or incident; rather, as specified by NTSB regulation, “accident/incident investigations are fact-finding proceedings with no formal issues and no adverse parties … and are not conducted for the purpose of determining the rights or liabilities of any person” (Title 49 Code of Federal Regulations section 831.4). Assignment of fault or legal liability is not relevant to the NTSB’s statutory mission to improve transportation safety by investigating accidents and incidents and issuing safety recommendations. In addition, statutory language prohibits the admission into evidence or use of any part of an NTSB report related to an accident in a civil action for damages resulting from a matter mentioned in the report (Title 49 United States Code section 1154(b)). A factual report that may be admissible under 49 United States Code section 1154(b) is available here.