ACCIDENT RECOVERY
and periodic preventive maintenance. MARPAT Aviation had copies of these, and the checklist it developed for its annual and 100-hour inspections while the aircraft was registered in the restricted category closely tracked the army manuals. Items 9 and 10 of the engine section of the daily check- list (relaxed to every 10 hours or 14 days in civilian service) mandated inspection of the exhaust diffuser, support cone, and second-stage turbine blades. Post-accident, each of these components were found to have incurred progressive damage preceding the eventual engine failure. The operating limitations of
What happens when the regulations themselves are confusing, ambiguous, or repeatedly changed in ways that don’t seem to make sense?
the aircraft’s last reregistration in the experimental exhibition category in December 2014 required only that it had to be inspected “in accordance with the scope and detail of 14 CFR § 43, Appendix D, and found to be in a condition for safe opera- tion.” The NTSB noted that the work orders from the aircraft’s two most recent annual inspec- tions referred only to Part
43, Appendix D, and found no evidence that the helicopter had been prepared for long periods of inactivity as stipulated in TM 55-1520-219-20, an oversight that likely contributed to “the extensive corrosion observed within the engine.” The oper- ator likewise didn’t conduct the inspection of the power turbine blades and exhaust diffuser called for in the army’s daily inspection manual and the Interagency Committee for Aviation Policy’s UH-1 Series Inspection Planning Guide (developed when the government began civilian sales of surplus Hueys). The NTSB report also goes into considerable
detail about a series of revisions in FAA Order 8130.2, which “establishes policies and proce- dures for issuing airworthiness certificates for aircraft.” Version G, issued in August 2010, placed the UH-1B in the category of turbine-powered aircraft with maximum gross takeoff weights less than 12,500 lb. Rotorcraft in this group oper- ated under experimental exhibition certificates were required to follow “a current inspection
62 POWER UP DEC 2024
program recommended by the manufacturer” or “any other inspection program … approved by the Administrator.” However, a memorandum of deviation issued in December 2011 relaxed this requirement to the standards of Part 43, Appendix D. Operations in the restricted category still required compliance with the standards of the army technical manuals, reflected in the operating limitations of N98F’s final registration under that classification. Version H of Order 8130.2 required former
military turbine-powered helicopters operated under experimental exhibition certificates to be maintained “under an inspection program rec- ommended by the helicopter manufacturer or a NATO military service.” It was issued on Feb. 4, 2015, two months after N98F’s last reregistration. The accident helicopter was therefore not subject to either this or the subsequent Version J, which advised FAA inspectors that Appendix D was “not sufficient to mitigate every safety risk you might encounter with a particular aircraft of operation” and recommended that they “prescribe additional operating limitations … based on inspections and assessments of potential safety hazards.”
FAA Oversight FAA surveillance of experimental exhibition air- craft follows only the general procedures for all Part 91 operations, which don’t involve any formal inspection schedules. Specifically, FAA inspec- tors aren’t required to monitor adherence to the operating limitations of those certificates. The investigation determined that MARPAT Aviation didn’t routinely comply with limitation No. 4, which required submission of annual program letters to the responsible Flight Standards District Office (FSDO) listing the “events at which the aircraft will be exhibited.” The FAA plans its surveillance on the basis of these program letters. MARPAT’s owner suggested that events at the aircraft’s base didn’t have to be reported, but no such pro- vision appeared in the operating limitations. The Charleston, West Virginia, FSDO’s principal main- tenance inspector (PMI) confirmed that the FSDO should have been notified of the Huey reunions. Carriage of passengers for compensation or hire is generally subject to CFR 14 Part 119.
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