2024-17-02: Rotorcraft Tail Boom

1. The authority citation for part 39 continues to read as follows: Authority: 49 U.S.C. 106(g), 40113, 44701. 2. The FAA amends § 39.13 by adding the following new airworthiness directive: 2024-17-02 Bell Textron Inc.: Amendment 39-22827; Docket No. FAA-2022-0600; Project Identifier AD-2021-01160-R. (a) Effective Date This airworthiness directive (AD) is effective November 8, 2024. (b) Affected ADs None. (c) Applicability This AD applies to Bell Textron Inc. Model 204B, 205A, 205A-1, 205B, and 210 helicopters, certificated in any category. (d) Subject Joint Aircraft System Component (JASC) 5302, Rotorcraft Tail Boom. (e) Unsafe Condition This AD was prompted by an accident and incidents involving failure of the tail boom attachment structure. The FAA is issuing this AD to address fatigue cracking of tail boom attachment fittings, cap angles, longerons, and bolts. The unsafe condition, if not addressed, could result in separation of the tail boom from the helicopter and subsequent loss of control of the helicopter. (f) Compliance Comply with this AD within the compliance times specified, unless already done. (g) Allowable Torque Values (in-lbs) Tail boom attachment point Model 204B Model 205A/205A-1 Model 205B Model 210 Upper left-hand bolt 570-610 1000-1200 1000-1200 1300-1600 Upper right-hand bolt 360-380 1000-1200 1000-1200 1000-1200 Lower left-hand bolt 360-380 400-430 400-430 400-430 Lower right-hand bolt 360-380 400-430 400-430 400-430 (h) Required Actions (1) Within 300 hours time-in-service (TIS) or 90 days after the effective date of this AD, whichever occurs first, accomplish the actions required by paragraphs (h)(1)(i), (ii), or (iii) of this AD as applicable to your model helicopter. For purposes of this AD, the word "new" is defined as having zero total hours TIS. (i) For Model 204B helicopters, accomplish the actions required by paragraphs (h)(1)(i)(A) through (C) of this AD. (A) With the tail boom assembly removed, remove the upper left-hand (LH) tail boom attachment bolt (bolt) from service and inspect its associated tail boom attachment nut (nut) for mechanical damage, corrosion, a crack, damaged threads, and wear, and to determine whether it is a steel alloy part number (P/N) NAS679A, NAS1291, or MS21042. If there is any mechanical damage, corrosion, a crack, a damaged thread, or wear, or if nut P/N NAS679A, NAS1291, or MS21042 is installed, before further flight, remove the nut from service. (B) Visually inspect each bulkhead (FS 195.00 and FS 195.03) and the bolt holes for mechanical damage, corrosion, and cracks; visually inspect each attachment fitting for mechanical damage, corrosion, cracks, and loose fasteners; determine if any of the three other nuts are a steel alloy P/N NAS679A, NAS1291, or MS21042; and visually inspect the other three nuts, the upper right-hand (RH) bolt, and two lower bolts for mechanical damage, corrosion, cracks, damaged threads, and wear, including the bolt shank and head radii of the bolts for a damaged thread, wear, and mechanical damage. ( 1 ) If there is any mechanical damage, corrosion, or cracks on any bulkhead (FS 195.00 or FS 195.03), or any mechanical damage, corrosion, or cracks on any bolt holes, or if there is any mechanical damage, corrosion, cracks, or loose fasteners on any attachment fitting, before further flight, repair or replace the affected bulkhead or the affected attachment fitting, as appropriate, in accordance with FAA-approved procedures. ( 2 ) If there is any mechanical damage, corrosion, a crack, a damaged thread, or wear on any nut, or if nut P/N NAS679A, NAS1291, or MS21042 is installed, before further flight, remove the affected nut from service. If there is a crack on any nut, before further flight, also remove its associated bolt from service. ( 3 ) If there is any mechanical damage, corrosion, a crack, a damaged thread, or wear on the on the upper RH bolt or two lower bolts, which includes the bolt shank or head radii, before further flight, remove the affected bolt from service. (C) Apply a coating of Aeriol ThixO #2 (3810-0) or Aeriol ThixO SYN (3820-0) aviation grease to each bolt shank only. Install the hardware set of each tail boom attachment point (nickel alloy nut P/N 90-132L7 or 90-132L6, as applicable to the affected tail boom attachment point, new upper LH bolt P/N NAS627-21, upper RH and two lower bolts P/N NAS626-20, countersunk washer, and plain washers). Torque each bolt by using the torque value information identified in paragraph (g) of this AD. (ii) For Model 205A, 205A-1, and 205B helicopters, accomplish the actions required by paragraphs (h)(1)(ii)(A) through (C) of this AD. (A) With the tail boom assembly removed, remove the upper LH bolt from service and inspect its associated tail boom attachment barrel nut (barrel nut) and retainer for mechanical damage, corrosion, a crack, damaged threads, and wear, and to determine whether it is a steel alloy barrel nut P/N NAS577B8A. If there is any mechanical damage, corrosion, a crack, a damaged thread, or wear, or if barrel nut P/N NAS577B8A is installed, before further flight, remove the barrel nut and its associated retainer from service. (B) Visually inspect each bulkhead (BS 17.31 and FS 243.89) and the bolt holes for mechanical damage, corrosion, and cracks; visually inspect each attachment fitting for mechanical damage, corrosion, cracks, and loose fasteners; determine if any of the three other barrel nuts are steel alloy P/N NAS577B8A or P/N NAS577B6A; and visually inspect the other three barrel nuts and the associated retainers, the upper RH bolt, and two lower bolts for mechanical damage, corrosion, cracks, damaged threads, and wear, including the bolt shank and head radii of the bolts for a damaged thread, wear, and mechanical damage. ( 1 ) If there is any mechanical damage, corrosion, or cracks on any bulkhead (BS 17.31 or FS 243.89), or any mechanical damage, corrosion, or cracks on any bolt holes, or if there is any mechanical damage, corrosion, cracks, or loose fasteners on any attachment fitting, before further flight, repair or replace the affected bulkhead or the affected attachment fitting, as appropriate, in accordance with FAA-approved procedures. ( 2 ) If there is any mechanical damage, corrosion, a crack, a damaged thread, or wear on any barrel nut or retainer, or if barrel nut P/N NAS577B8A or NAS577B6A is installed, before further flight, remove the affected barrel nut and retainer (as a pair) from service. If there is a crack on any nut, before further flight, also remove its associated bolt from service. ( 3 ) If there is any mechanical damage, corrosion, a crack, a damaged thread, or wear on the upper RH bolt or two lower bolts, which includes the bolt shank or head radii, before further flight, remove the affected bolt from service. (C) Apply a coating of Aeriol ThixO #2 (3810-0) or Aeriol ThixO SYN (3820-0) aviation grease to each bolt shank only. Install the hardware set of each tail boom attachment point (nickel alloy barrel nut P/N NAS577C6A or P/N NAS577C8A and retainer P/N NAS578C6A or P/N NAS578C8A, as applicable to the affected tail boom attachment point, new upper LH bolt P/N NAS628-22, upper RH and two lower bolts P/N NAS628-22 or NAS626-18, as applicable to the affected tail boom attachment point, countersunk washer, and plain washers). Torque each bolt by using the torque value information identified in paragraph (g) of this AD. (iii) For Model 210 helicopters, accomplish the actions required by paragraphs (h)(1)(iii)(A) through (C) of this AD. (A) With the tail boom supported, remove the upper LH bolt, and the steel alloy barrel nut P/N NAS577B9A, including the retainer, from service. Remove the countersunk washer, and plain washers, and install new nickel alloy barrel nut P/N NAS577C9A, new retainer P/N NAS578C9A, airworthy countersunk washer, airworthy plain washers, and a new bolt in accordance with the Accomplishment Instructions, Part I, paragraphs 5 through 7 of Bell Alert Service Bulletin (ASB) 210-21-15, Revision A, dated February 23, 2022 (ASB 210-21-15, Rev A). (B) Remove the upper RH bolt, steel alloy barrel nut P/N NAS577B8A, countersunk washer, and plain washers. Visually inspect the upper RH bolt for any corrosion, damaged threads, wear, and fatigue cracking. If the upper RH bolt has any corrosion, damaged threads, wear, or fatigue cracking, before further flight, remove the upper RH bolt from service. Visually inspect the removed barrel nut for cracking. If there is any cracking in the barrel nut, before further flight, remove the upper RH bolt from service. Regardless of the result of the upper RH steel alloy barrel nut inspection, replace the barrel nut with a new nickel alloy barrel nut P/N NAS577C8A and new retainer P/N NAS578C8A. Install a new upper RH bolt or reinstall the existing upper RH bolt (if no cracks in the barrel nut, and no corrosion, damaged threads, wear, or fatigue cracking in the bolt were identified), by following the Accomplishment Instructions, part I, paragraphs 11 and 12, including the caution above paragraph 11, of ASB 210-21-15, Rev A. (C) Remove one of the lower bolts, its lower steel alloy barrel nut P/N NAS577B6A, countersunk washer, and plain washers. Visually inspect that lower bolt for any corrosion, damaged threads, wear, and fatigue cracking. If the lower bolt has any corrosion, damaged threads, wear, or fatigue cracking, before further flight, remove the lower bolt from service. Visually inspect the removed lower barrel nut for cracking. If there is any cracking in the lower barrel nut, before further flight, remove the lower bolt from service. Regardless of the result of that lower steel alloy barrel nut inspection, replace the barrel nut with a new nickel alloy barrel nut P/N NAS577C6A and new retainer P/N NAS578C6A. Install a new lower bolt or reinstall the existing lower bolt (if no cracks in the barrel nut, and no corrosion, damaged threads, wear, or fatigue cracking in the bolt were identified), by following the Accomplishment Instructions, part I, paragraphs 16 through 17, including the caution above paragraph 16, of ASB 210-21-15, Rev A. Repeat the actions required by this paragraph for the other lower attachment point. (2) After accumulating 1 hour TIS, but not to exceed 5 hours TIS, after accomplishing the actions required by paragraph (h)(1) of this AD, using the torque value information identified in paragraph (g) of this AD applicable to your model helicopter, inspect the torque applied on each bolt. Thereafter, repeat the torque inspection of each bolt after accumulating 1 hour TIS, but not to exceed 5 hours TIS, to determine if the torque has stabilized. Do not exceed three torque inspections total for each bolt and accomplish the actions required by paragraphs (h)(2)(i) and (ii) of this AD. (i) If the torque on a bolt is below the minimum allowable torque limit as a result of any instance of the torque inspection or if after three torque inspection attempts, the torque on any bolt has not stabilized, before further flight, accomplish the actions required by paragraphs (h)(2)(i)(A) and (B) of this AD. (A) Remove the hardware set of one failed tail boom attachment point (nut, bolt, countersunk washer, and plain washers for Model 204B helicopters, and barrel nut, bolt, retainer, countersunk washer, and plain washers for Model 205A, 205A-1, 205B, and 210 helicopters). For Model 204B helicopters, remove the nut from service and for Model 205A, 205A-1, 205B, and 210 helicopters, remove the barrel nut and retainer from service as applicable to the affected tail boom attachment point. Visually inspect the removed bolt for any corrosion, damaged threads, wear, and fatigue cracking. If the bolt has any corrosion, a damaged thread, wear, or fatigue cracking, before further flight, remove the bolt from service. (B) Apply a coating of Aeriol ThixO #2 (3810-0) or Aeriol ThixO SYN (3820-0) aviation grease to the bolt shank only. Install a new bolt or reinstall the existing bolt (if no corrosion, damaged threads, wear, or fatigue cracking in the bolt were identified) and the hardware set of the affected tail boom attachment point (new nut P/N 90-132L6 or 90-132L7, countersunk washer, and plain washers for Model 204B helicopters, and new nickel alloy barrel nut P/N NAS577C6A, NAS577C8A or P/N NAS577C9A and new retainer P/N NAS578C6A, NAS578C8A, or P/N NAS577C9A, countersunk washer, and plain washers for Model 205A, 205A-1, 205B, and 210 helicopters), as applicable to the affected tail boom attachment point. Torque the bolt by using the torque value information identified in paragraph (g) of this AD. Repeat the actions required by paragraphs (h)(2)(i)(A) and (B) of this AD for each failed tail boom attachment point, one hardware set at a time. Then repeat the actions required by paragraph (h)(2) of this AD just for each newly installed or reinstalled bolt until the torque for all four tail boom attachment points stabilize. (ii) If the torque for all four tail boom attachment points has stabilized, before further flight, apply a torque stripe to all four bolts. (3) Within 600 hours TIS or 12 months, whichever occurs first after applying torque stripes to all four bolts as required by paragraph (h)(2)(ii) of this AD, and thereafter within intervals not to exceed 600 hours TIS or 12 months, whichever occurs first, inspect the torque applied on each bolt using the torque value information identified in paragraph (g) of this AD, as applicable to your model helicopter. If the torque on any bolt is below the minimum allowable torque limit, accomplish the actions required by paragraphs (h)(3)(i) and (ii) of this AD. (i) Before further flight, remove the hardware set of one failed tail boom attachment point (nut, bolt, countersunk washer, and plain washers for Model 204B helicopters, and barrel nut, retainer, bolt, countersunk washer, and plain washers for Model 205A, 205A-1, 205B, and 210 helicopters) and then accomplish the actions required by paragraphs (h)(3)(i)(A), (B), or (C) of this AD as applicable to your model helicopter. (A) For Model 204B helicopters, visually inspect the removed nut for cracking, corrosion, and loss of tare torque. If the nut has any cracking, corrosion, or loss of tare toque, before further flight, remove the nut from service and replace with a new nut P/N 90-132L7 or 90-132L6 as applicable to the tail boom attachment point. Regardless of the result of the nut inspection, remove the bolt from service and replace it with a new bolt by applying a coating of Aeriol ThixO #2 (3810-0) or Aeriol ThixO SYN (3820-0) aviation grease to the bolt shank only, and install the hardware set of the tail boom attachment point (nut, bolt, and countersunk washer, and plain washers). Torque each bolt by using the torque value information identified in paragraph (g) of this AD. Repeat the actions required by this paragraph for each failed tail boom attachment point, one hardware set at a time. (B) For Model 205A, 205A-1, and 205B helicopters, visually inspect the removed barrel nut for cracking, corrosion, and loss of tare torque. If the barrel nut has any cracking, corrosion, or loss of tare toque, before further flight, remove the barrel nut and retainer from service and replace them with a new nickel alloy barrel nut P/N NAS577C6A, or NAS577C8A, and new retainer P/N NAS578C6A, or NAS578C8A, with the P/N of the new nickel alloy barrel nut and the P/N of the new retainer being as applicable to the affected tail boom attachment point. Regardless of the result of the barrel nut inspection, remove the bolt from service and replace it with a new bolt. Apply a coating of Aeriol ThixO #2 (3810-0) or Aeriol ThixO SYN (3820-0) aviation grease to each bolt shank only. Install the hardware set of each tail boom attachment point (nickel alloy barrel nut, retainer, bolt, countersunk washer, and plain washers). Torque each bolt by using the torque value information identified in paragraph (g) of this AD. Repeat the actions required by this paragraph for each failed tail boom attachment point, one hardware set at a time. (C) For Model 210 helicopters, visually inspect the removed barrel nut for cracking, corrosion, and loss of tare torque. If the barrel nut has any cracking, corrosion, or loss of tare toque, before further flight, remove the barrel nut and retainer from service and replace them with a new nickel alloy barrel nut P/N NAS577C6A, NAS577C8A, or NAS577C9A, and new retainer P/N NAS578C6A, NAS578C8A, or NAS578C9A, with the P/N of the new nickel alloy barrel nut and the P/N of the new retainer being as applicable to the affected tail boom attachment point. Regardless of the result of the barrel nut inspection, remove the bolt from service and replace it with a new bolt, apply a coating of Aeriol ThixO #2 (3810-0) or Aeriol ThixO SYN (3820-0) aviation grease to each bolt shank only, and torque each bolt by using the torque value information identified in paragraph (g) of this AD. Repeat the actions required by this paragraph for each failed tail boom attachment point, one hardware set at a time. (ii) After accumulating 1 hour TIS, but not to exceed 5 hours TIS after accomplishing the actions required by paragraph (h)(3)(i) of this AD, using the torque value information identified in paragraph (g) of this AD as applicable to your model helicopter, inspect the torque applied on each newly installed bolt. Thereafter, repeat the torque inspection of those bolts after accumulating 1 hour TIS, but not to exceed 5 hours TIS, to determine if the torque has stabilized. Do not exceed three torque inspections total for those bolts and accomplish the actions required by paragraphs (h)(2)(i) and (ii) of this AD. (4) Within 5,000 hours TIS or 5 years after accomplishing the actions required by paragraph (h)(1) of this AD, whichever occurs first, and thereafter within intervals not to exceed 5,000 hours TIS or 5 years, whichever occurs first, accomplish the actions required by paragraphs (h)(4)(i) and (ii) of this AD. (i) Accomplish the actions required by paragraphs (h)(1)(i), (ii), or (iii) of this AD, as applicable to your model helicopter. (ii) After accumulating 1 hour TIS, but not to exceed 5 hours TIS after accomplishing the actions required by paragraph (h)(4)(i) of this AD, using the torque value information identified in paragraph (g) of this AD as applicable to your model helicopter, inspect the torque applied on each bolt. Thereafter, repeat the torque inspection of those bolts after accumulating 1 hour TIS, but not to exceed 5 hours TIS, to determine if the torque has stabilized. Do not exceed three torque inspections total for those bolts and accomplish the actions required by paragraphs (h)(2)(i) and (ii) of this AD. (5) As of the effective date of this AD, do not install the following parts identified in paragraphs (h)(5)(i) and (ii) of this AD on any helicopter. (i) For Model 204B helicopters: steel alloy nut P/N NAS679A, NAS1291, or MS21042. (ii) For Model 205A, 205A-1, 205B, and 210 helicopters: steel alloy barrel nut P/N NAS577B9A, P/N NAS577B8A, or P/N NAS577B6A. (i) Special Flight Permit A one-time special flight permit may be issued in accordance with 14 CFR 21.197 and 21.199 in order to fly to a maintenance area to perform the required actions in this AD. (j) Alternative Methods of Compliance (AMOCs) (1) The Manager, Central Certification Branch, FAA, has the authority to approve AMOCs for this AD, if requested using the procedures found in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request to your principal inspector or local Flight Standards District Office, as appropriate. If sending information directly to the manager of the certification office, send it to the attention of the person identified in paragraph (k) of this AD. Information may be emailed to AMOC@faa.gov. (2) Before using any approved AMOC, notify your appropriate principal inspector, or lacking a principal inspector, the manager of the local flight standards district office/certificate holding district office. (k) Related Information For more information about this AD, contact Michael Perrin, Aviation Safety Engineer, FAA, 1801 S Airport Road, Wichita, KS 67209; phone: (562) 627-5362; email: Michael.j.perrin@faa.gov. (l) Material Incorporated by Reference (1) The Director of the Federal Register approved the incorporation by reference of the material listed in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51. (2) You must use this material as applicable to do the actions required by this AD, unless the AD specifies otherwise. (i) Bell Alert Service Bulletin 210-21-15, Revision A, dated February 23, 2022. (ii) [Reserved] (3) For Bell material identified in this AD, contact Bell Textron Inc., P.O. Box 482, Fort Worth, TX 76101; phone: (450) 437-2862 or (800) 363-8023; fax: (450) 433-0272; email: productsupport@bellflight.com; website: bellflight.com/support/contact-support. (4) You may view this material at the FAA, Office of Regional Counsel, Southwest Region, 10101 Hillwood Pkwy., Fort Worth, TX 76177. For information on the availability of this material at the FAA, call: (817) 222-5110. (5) You may view this material at the National Archives and Records Administration (NARA). For information on the availability of this material at NARA, visit www.archives.gov/federal-register/cfr/ibr-locations or email fr.inspection@nara.gov . Issued on September 27, 2024. Victor Wicklund, Deputy Director, Compliance & Airworthiness Division, Aircraft Certification Service. [FR Doc. 2024-22908 Filed 10-3-24; 8:45 am]BILLING CODE 4910-13-P