Airworthiness Directive · Amendment 39-17485 · Rotorcraft tailboom
Bell Helicopter Textron Canada Helicopters
Superseded. A later AD replaced this one: AD 2022-23-02. Comply with the one in force.
This AD applies to BHTC Model 407 helicopters, with tailboom assembly part number (P/N) 407-030-801-201, 407-030-801-203, or 407-030-801-205, certificated in any category.
We are adopting a new airworthiness directive (AD) for Bell Helicopter Textron Canada (BHTC) Model 407 helicopters with certain tailboom assemblies installed. This AD requires, at specified intervals, inspecting the tailboom assembly for a crack, loose rivet, or other damage. This AD was prompted by a stress analysis of the tailboom skin that revealed that high-stress-concentration areas are susceptible to skin cracking. This condition, if not detected, could result in a crack in the tailboom assembly, failure of the tailboom, and subsequent loss of control of the helicopter.
You are responsible for performing each action required by this AD within the specified compliance time unless it has already been accomplished prior to that time.
(1) For helicopters with a tailboom assembly that has 8,600 or more hours time-in-service (TIS):
(i) Comply with either paragraph (e)(1)(i)(A) or (e)(1)(i)(B):
(A) Before the first flight of each day, visually check for a crack in the “C” and “D” areas depicted in Figures 1and 2 to Paragraph (e) of this AD. The actions required by this paragraph may be performed by the owner/operator (pilot) holding at least a private pilot certificate, and must be entered into the aircraft records showing compliance with this AD in accordance with 14 CFR 43.9 (a)(1)-(4) and 14 CFR § 91.417(a)(2)(v). The record must be maintained as required by 14 CFR 91.417, 121.380, or 135.439; or
(B) Within 25 hours TIS, or 30 days, whichever comes first, and thereafter at intervals not to exceed 50 hours TIS, clean and inspect for a crack around each fastener and just above the edge of the upper stabilizer support in the “C” and “D” areas on the left side of the tailboom assembly, as depicted in Figure 2 to Paragraph (e) of this AD, using a 10X or higher power magnifying glass.
(ii) Comply with the requirements of paragraph (e)(2)(i)(A) or (e)(2)(i)(B), and paragraph (e)(3) of this AD.
(2) For helicopters with a tailboom assembly that has 6,900 or more hours TIS:
(i) Within 25 hours TIS or 30 days, whichever occurs first, clean and inspect the tailboom assembly for a crack in the “H” and “I” areas depicted in Figure 2, Sheet 5, of the BHTC Alert Service Bulletin No. 407-08-84, dated August 18, 2008, (ASB), by using one of the two following methods.
(A) Use a 10X or higher power magnifying glass; thereafter, repeat the 10X or higher power magnifying glass inspection at intervals not to exceed 150 hours TIS; or
(B) Eddy current inspect for a crack in accordance with Appendix A and Table 1, and by referencing Figures 3 through 7 of the ASB; thereafter, repeat the eddy current inspection at intervals not to exceed 500 hours TIS. Use a person qualified to Level II or Level III per the National Aerospace Standard (NAS) 410 or equivalent requirements to perform the eddy current inspection.
(ii) Comply with the requirements of paragraph (e)(3) of this AD.
(3) Within 100 hours TIS or at the next tailboom inspection, whichever comes first, and thereafter at intervals not to exceed 300 hours TIS:
(i) Clean and inspect the tailboom assembly for a loose rivet, a crack, or other damage in accordance with Part II, paragraphs 2 and 3, of the ASB; and
(ii) Using a 10X or higher power magnifying glass, inspect the tailboom assembly for a loose rivet or a crack in accordance with Part II, paragraphs 4 through 6, of the ASB.
(4) If the total accumulated hours TIS on the tailboom assembly is unknown, assume the tailboom assembly has 8,600 or more hours TIS and clean and inspect in accordance with paragraph (e)(1) of this AD.
(5) If there is a crack in the tailboom assembly, before further flight, replace it with an airworthy tailboom assembly.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.