FAA: More Bell Models Require Rotor Hub Inspections

Bell Helicopters 204B
Credit: wikimedia.commons

The FAA issued a second emergency airworthiness directive (AD) this week that requires operators of additional models of Bell helicopters to inspect their main-rotor hubs for potentially faulty hub strap pins.

Issued on July 9, FAA AD 2021-15-52 covers restricted-category helicopters primarily used by the military, law-enforcement agencies, and forest and wildlife conservation services, as well as for mineral exploration and other purposes. The directive affects an estimated 359 restricted-category helicopters registered in the U.S. and 529 worldwide.

The latest AD follows emergency directives issued on July 5 and 6, respectively, by Transport Canada (CF-2021-23) and the FAA (AD 2021-15-51) requiring main-rotor hub inspections on Bell 204B, 205A-1, 205B and 212 models. The previous directives affected about 140 standard-category helicopters in the U.S. and 400 worldwide, according to the FAA.

Aviation authorities issued the directives following the June 28 crash of a Yellowhead Helicopters Bell 212 during firefighting operations near Evansburg, Alberta, west of Edmonton. The crash killed the pilot, the helicopter’s only occupant.

Investigators discovered an outboard main rotor hub strap pin with Part Number (P/N) 204-012-104-005 and the Serial Number Prefix FNFS had sheared off during flight, which resulted in the main rotor blade and main rotor head detaching from the helicopter. The pin had accumulated only 20 total hours of time in service.

Although defective strap pins were found only on the accident helicopter and another Bell 212 examined by Canadian investigators, strap pins of the same P/N also can be installed on Bell 204Bs, 205A-1s and 205Bs. The earlier directives called for main-rotor hub inspections of those models and replacements of strap pins with the serial number prefix FNFS. Bell Textron issued Alert Service Bulletins (ASB) on July 5 describing the requirement.

After issuing its July 6 directive, the FAA determined that hub strap P/N 204-012-104-005 with the Serial Number Prefix FNFS also could be installed on restricted-category helicopters originally manufactured by Bell Textron. FAA AD 2021-15-52 expands the inspection and replacement requirement to the following models:

  • Rotorcraft Development Corp. Model HH-1K.
  • Robinson Air Crane, Rotorcraft Development Corp. and Tamarack Helicopters Model TH-1F.
  • Bell Textron Overseas Aircraft Support Inc. (a type certificate previously held by JTBAM) and Rotorcraft Development Corp. Model TH-1L.
  • Richards Heavylift Helo, Model UH-1A.
  • International Helicopters, Overseas Aircraft Support Red Tail Flying Services, Richards Heavylift Helo, Rotorcraft Development Corp., Southwest Florida Aviation International and WSH LLC (a type certificate previously held by San Joaquin Helicopters), Model UH-1B.
  • Bell Textron, Overseas Aircraft Support, Rotorcraft Development Corp., Smith Helicopters and West Coast Fabrications Model UH-1E.
  • AST, California Department of Forestry, Robinson Air Crane, Rotorcraft Development Corp. and Tamarack Helicopters Model UH-1F.
  • Arrow Falcon Exporters, Global Helicopter Technology, Hagglund Helicopters, JJASPP Engineering Services, Northwest Rotorcraft, Overseas Aircraft Support, Richards Heavylift Helo, Rotorcraft Development Corp., Southwest Florida Aviation International and Tamarack Helicopters Model UH-1H.
  • Bell Textron, Overseas Aircraft Support and Rotorcraft Development Corp. Model UH-1L. 
  • Robinson Air Crane and Rotorcraft Development Corp. Model UH-1P.
Bill Carey

Based in Washington, DC, Bill covers avionics, air traffic management and aviation safety for Aviation Week. A former daily newspaper reporter, he has covered the commercial, business and military aviation segments as well as unmanned aircraft systems. Prior to joining Aviation Week in November 2017, he worked for Aviation International News and Avionics and Rotor & Wing magazines.