The attached letter from the NTSB Chair provides information about the Collision with Powerlines and Terrain during Forced Landing MARPAT Aviation Bell Helicopter UH-1B, N98F Amherstdale, West Virginia June 22, 2022. The details of this accident investigation and the resulting safety recommendations may be found in the attached report, which can also be accessed at http://www.ntsb.gov.
The NTSB is vitally interested in these recommendations because they are designed to prevent accidents and save lives. We would appreciate a response within 90 days of the date of this letter detailing the actions you have taken or intend to take to implement these recommendations. When replying, please refer to the safety recommendations by number (for example, A-24-20 through -25). We encourage you to submit your response to ExecutiveSecretariat@ntsb.gov. If your reply exceeds 20 megabytes, including attachments, please e mail us at the same address for instructions on how to send larger documents. Please do not submit both an electronic copy and a hard copy of the same response.
This letter provides information about the National Transportation Safety Board’s (NTSB) August 14, 2024, report Collision with Powerlines and Terrain during Forced Landing MARPAT Aviation Bell Helicopter UH-1B, N98F (NTSB/AIR-24-04). The details of this accident investigation and the resulting safety recommendations may be found in the attached report, which can also be accessed at http://www.ntsb.gov.
As a result of this investigation, we identified the following safety issues:
• the need to review all experimental exhibition airworthiness certificates issued to turbine-powered rotorcraft.
• the need for periodic reviews for experimental exhibition airworthiness certificates.
• the need for recurrent inspections of aircraft equipped with Ozark Aeroworks T53-series engines.
• the need for operators of experimental exhibition aircraft to submit a list all events at which the aircraft will be exhibited.
• the need for a method to ensure that operators of experimental exhibition aircraft meet their annual obligation to submit program letters.
• the need for inspector guidance that requires routine surveillance of operators of aircraft with experimental exhibition airworthiness certificates.
Accordingly, the NTSB makes the following safety recommendations to the Federal Aviation Administration (FAA). Additional information regarding these recommendations can be found in the noted sections of the report.
• Review all experimental exhibition airworthiness certificates issued to turbine-powered rotorcraft and ensure that their operating limitations meet the standards of the latest iteration of Federal Aviation Administration Order 8130.2, Airworthiness Certification of Aircraft. (A 24 20) (See section 2.4.)
• Establish periodic reviews for experimental exhibition airworthiness certificates to ensure that those aircraft are being inspected and maintained according to the latest iteration of Federal Aviation Administration Order 8130.2, Airworthiness Certification of Aircraft. (A-24-21) (See section 2.4.)
• Require operators of aircraft equipped with Ozark Aeroworks T53-series engines to perform recurrent inspections of the rear bearing cover and the exhaust diffuser inner cone and inner struts with the exhaust diffuser cover removed. (A-24-22)
(See section 2.5.)
• Remind operators of experimental exhibition aircraft about the requirement to submit, to the appropriate flight standards district office, program letters that list all events at which the aircraft will be exhibited. (A-24-23) (See section 2.6)
• Develop a method for ensuring that operators of experimental exhibition aircraft meet their annual obligation to submit program letters; such a method could include potential penalties for operators that do not meet this obligation. (A 24-24) (See section 2.6)
• Revise Federal Aviation Administration Order 8900.1, Flight Standards Information Management System, to include inspector guidance requiring routine surveillance of operators of aircraft with experimental exhibition airworthiness certificates. (A 24 25) (See section 2.6)
In addition, the NTSB reiterates the following recommendation to the FAA:
Develop national safety standards, or equivalent regulations, for revenue passenger-carrying operations that are currently conducted under Title 14 Code of Federal Regulations Part 91, including, but not limited to, sightseeing flights conducted in a hot air balloon, intentional parachute jump flights, and living history flight experience and other vintage aircraft flights. These standards, or equivalent regulations, should include, at a minimum for each operation type, requirements for initial and recurrent training and maintenance and management policies and procedures. (A-21-9)
The NTSB is vitally interested in these recommendations because they are designed to prevent accidents and save lives. We would appreciate a response within 90 days of the date of this letter, detailing the actions you have taken or intend to take to implement these recommendations. When replying, please refer to the safety recommendations by number (Safety Recommendations A-24-20 through -25 and reiterated Safety Recommendation A-21-9.) We encourage you to submit your response to ExecutiveSecretariat@ntsb.gov. If your reply, including attachments, exceeds 20 megabytes, please e mail us at the same address for instructions on how to send larger documents.
Please do not submit both an electronic copy and a hard copy of the same response.
Aviation Investigation Report AIR-24-04 Collision with Powerlines and Terrain during Forced Landing MARPAT Aviation Bell Helicopter UH-1B, N98F Amherstdale, West Virginia June 22, 2022 report published on August 27, 2024:
Operator Inspection and Maintenance of Helicopter
From December 5, 2014, to the date of the accident, the helicopter was certificated under a special experimental exhibition airworthiness certificate. During that time, MARPAT Aviation performed inspections of the helicopter according to the generic inspection criteria for aircraft systems and components in Appendix D to 14 CFR Part 43, as required.
However, when the accident helicopter was operated under a restricted-category airworthiness certificate (before December 2014), MARPAT Aviation was required, by the associated operating limitations, to maintain the helicopter according to more comprehensive inspection standards, which were reflected in the checklist that the operator developed for those inspections. Table 3 compares the requirements of Part 43 Appendix D with the operator’s checklist when the helicopter was operated under a restricted-category certificate.
A comparison of the inspection requirements for the engine components that failed on the accident helicopter showed that, unlike Appendix D paragraphs (d)(3) and (d)(8), MARPAT Aviation checklist numbers 9 and 10 required inspections of the specific components with progressive damage that preceded the engine failure.
Table 3. Comparison of engine inspection requirements for the accident helicopter’s experimental- and restricted-category certificates.
Title 14 CFR Part 43 Appendix D requirements for helicopter while under an experimental-category certificate MARPAT Aviation 100-hour/annual inspection requirements for helicopter while under a restricted category certificate
(d) Each person performing an annual or [a] 100-hour inspection shall inspect (where applicable) components of the engine and nacelle group as follows:
(1) Engine section—for visual evidence of excessive oil, fuel, or hydraulic leaks, and sources of such
leaks.
(2) Studs and nuts—for improper torquing and obvious defects.
(3) Internal engine—for cylinder compression and for metal particles or foreign matter on screens and sump drain plugs. If there is weak cylinder compression, for improper i