# AD 2001-04-14: Fuselage Frame - Type: Airworthiness directive - Status: Current - Products: Airbus Helicopters AS355E, AS355F, AS355F1, AS355F2, AS355N, AS350B, AS350B1, AS350B2, AS350B3, AS350BA, AS350C, AS350D and 1 more - Effective: April 10, 2001 - Published: March 6, 2001, 66 FR 13413–13414 - Issued: February 20, 2001 - Issued as: Final rule - Supersedes: [AD 85-14-06 R1](https://openairdocs.org/ad/85-14-06-R1) - Superseded by: Nothing supersedes this AD - Product type: Aircraft, Rotorcraft - Amendment: 39-12133 - Docket: 2000-SW-17-AD - Registered aircraft: 951 may be affected, by airframe or engine model (OpenAirDocs) - Official PDF: https://openairdocs.org/files/sha256/8f/41/8f41af394e5fda071bfacbe07547f8b240335d53bab3d9be921e2c1faab0379a (from https://www.govinfo.gov/content/pkg/FR-2001-03-06/pdf/01-5167.pdf) - Federal Register: https://www.federalregister.gov/documents/2001/03/06/01-5167/airworthiness-directives-eurocopter-france-model-as350b-as350b1-as350b2-as350b3-as350ba-as350c - FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/255A37DB0AE3C60886256A470048499B.0001 - DRS record last changed: November 21, 2025 - Page: https://openairdocs.org/ad/2001-04-14 ## Summary This amendment supersedes an existing airworthiness directive (AD) for Societe Nationale Industrielle Aerospatiale (currently Eurocopter France) Model AS350 and AS355 series helicopters that currently requires inspecting the fuselage frame (frame) for a crack at the fuselage-to-tailboom interface and replacing or repairing, as necessary. That AD also requires a fastener torque check and retorquing, as necessary. This amendment retains the requirements of the existing AD but would increase the inspection interval from 1,200 hours time-in-service (TIS) to 2,500 hours or 6 years TIS, whichever occurs first. This amendment revises the time interval for inspecting the frame at the fuselage-to-tailboom interface to coincide with the inspection interval specified in the maintenance manual. The actions specified by this AD are intended to eliminate confusion and unnecessary costs and to prevent a cracked frame, tailboom failure, and subsequent loss of control of the helicopter. ## The airworthiness directive ### Adoption of the Amendment Accordingly, pursuant to the authority delegated to me by the Administrator, the Federal Aviation Administration amends part 39 of the Federal Aviation Regulations (14 CFR part 39) as follows: 1. The authority citation for part 39 continues to read as follows: 2. Section 39.13 is amended by removing Amendment 39-5089 (50 FR 28561, July 15, 1985) and Amendment 39-5121 (50 FR 37173, September 12, 1985), and by adding a new airworthiness directive (AD), Amendment 39-12133, to read as follows: 2001-04-14 Eurocopter France: Amendment 39-12133. Docket No. 2000-SW-17-AD. Supersedes AD 85-14-06, Amendment 39-5089, and AD 85-14-06 R1, Amendment 39-5121, Docket No. 85-ASW-15. Applicability: Model AS350B, AS350B1, AS350B2, AS350B3, AS350BA, AS350C, AS350D, AS350D1, AS355E, AS355F, AS355F1, AS355F2, and AS355N helicopters, certificated in any category. Note 1: This AD applies to each helicopter identified in the preceding applicability provision, regardless of whether it has been otherwise modified, altered, or repaired in the area subject to the requirements of this AD. For helicopters that have been modified, altered, or repaired so that the performance of the requirements of this AD is affected, the owner/operator must request approval for an alternative method of compliance in accordance with paragraph (e) of this AD. The request should include an assessment of the effect of the modification, alteration, or repair on the unsafe condition addressed by this AD; and if the unsafe condition has not been eliminated, the request should include specific proposed actions to address it. Compliance: Required as indicated, unless accomplished previously. To eliminate confusion and unnecessary costs and to prevent a cracked fuselage frame (frame), tailboom failure, and subsequent loss of control of the helicopter, accomplish the following: (a) Inspect the fuselage-to-tailboom attachment bolts in accordance with paragraph (d) for this AD within 30 hours time-in-service (TIS). (b) Inspect the fuselage-to-tailboom attachment bolts in accordance with paragraph (d) for this AD within 30 hours TIS of replacing or reinstalling a tailboom. (c) Repeat the inspection in accordance with paragraph (d) of this AD at intervals not to exceed 2500 hours or 6 years TIS, whichever occurs first. (d) Inspect the fuselage-to-tailboom attachment bolts for proper torque range and the frame, part number 350A21-1247-00, for a crack at the fuselage-to-tailboom interface. (1) Procedure for inspecting proper torque range: (i) Using a fine-point felt tip pen, mark the position of the nut relative to the assembly. (ii) One at a time, slightly loosen each nut. Do not allow the corresponding bolt to rotate relative to the assembly. (iii) Tighten the nut with a properly calibrated torque wrench until the mark on the nut lines up with the mark on the assembly. (iv) Record the torque value required to line up the two marks. (2) Interpretation of the recorded torque values for each nut: (i) If the torque value is less than 0.3 mdaN (26 in-lbs) on any nut: (A) Remove the tailboom. (B) Perform a dye-penetrant inspection for a crack in the bending radius of the frame. (C) If a crack is found, repair or replace the frame with an airworthy frame before further flight. (ii) If the torque value is between 0.3 mdaN and 1 mdaN (26 to 88 in-lbs), re-torque to 0.75 mdaN to 0.9 mdaN (67 to 79 in-lbs). (iii) If the torque value is equal to or greater than 1 mdaN (88 in-lbs), remove the nut and bolt and replace them with a new nut and bolt. Torque the nut to 0.75 mdaN to 0.9 mdaN (67-79 in-lbs). Note 2: Aerospatiale Service Bulletins AS 355 No. 05.14 and AS 350 No. 05.16 pertain to the subject of this AD. (e) An alternative method of compliance or adjustment of the compliance time that provides an acceptable level of safety may be used if approved by the Manager, Regulations Group, Rotorcraft Directorate, FAA. Operators shall submit their requests through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Regulations Group. Note 3: Information concerning the existence of approved alternative methods of compliance with this AD, if any, may be obtained from the Regulations Group. (f) Special flight permits may be issued in accordance with 14 CFR 21.197 and 21.199 to operate the helicopter to a location where the requirements of this AD can be accomplished. (g) This amendment becomes effective on April 10, 2001. ## Rule preamble ### Effective date April 10, 2001. ### For further information contact Jim Grigg, Aviation Safety Engineer, FAA, Rotorcraft Directorate, Regulations Group, Fort Worth, Texas 76193-0111, telephone (817) 222-5490, fax (817) 222-5961. ### SUPPLEMENTARY INFORMATION A proposal to amend part 39 of the Federal Aviation Regulations (14 CFR part 39) by superseding AD 85-14-06, Amendment 39-5089 (50 FR 28561, July 15, 1985) and AD 85-14-06 R1, Amendment 39-5121 (50 FR 37173, September 12, 1985), which apply to Societe Nationale Industrielle Aerospatiale (currently Eurocopter France) Model AS350 and AS355 series helicopters, was published in the Federal Register on December 8, 2000 (65 FR 76953). That action proposed the same actions as the existing AD's and also proposed increasing the inspection interval from 1,200 hours TIS to 2,500 hours or 6 years TIS, whichever occurs first, to coincide with the maintenance manual and eliminate confusion and unnecessary costs. To compensate for the increase in the inspection interval, reducing the initial inspection interval from 100 hours TIS to 30 hours TIS and changing the visual inspection to a dye-penetrant inspection were also proposed. Interested persons have been afforded an opportunity to participate in the making of this amendment. No comments were received on the proposal or the FAA's determination of the cost to the public. The FAA has determined that air safety and the public interest require the adoption of the rule as proposed. The FAA estimates that 475 helicopters of U.S. registry will be affected by this AD, that it will take approximately 8 work hours per helicopter to accomplish the required actions, and that the average labor rate is $60 per work hour. Based on these figures, the total cost impact of this AD on U.S. operators is estimated to be $228,000, assuming no cracked frames are discovered. The regulations adopted herein will not have a substantial direct effect on the States, on the relationship between the national Government and the States, or on the distribution of power and responsibilities among the various levels of government. Therefore, it is determined that this final rule does not have federalism implications under Executive Order 13132. For the reasons discussed above, I certify that this action (1) is not a “significant regulatory action” under Executive Order 12866; (2) is not a “significant rule” under DOT Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); and (3) will not have a significant economic impact, positive or negative, on a substantial number of small entities under the criteria of the Regulatory Flexibility Act. A final evaluation has been prepared for this action and it is contained in the Rules Docket. A copy of it may be obtained from the Rules Docket at the FAA, Office of the Regional Counsel, Southwest Region, 2601 Meacham Blvd., Room 663, Fort Worth, Texas. ## Affected data sheets (2) (OpenAirDocs) The type certificate data sheets whose models the AD names. - [TCDS H9EU](https://openairdocs.org/tcds/H9EU): Airbus Helicopters; names 8 of 10 models: AS350C, AS350B3, AS350B, AS350D1, AS350B2, AS350B1, AS350D, AS350BA - [TCDS H11EU](https://openairdocs.org/tcds/H11EU): Airbus Helicopters; names 5 of 6 models: AS355N, AS355F2, AS355F1, AS355E, AS355F ## Registered aircraft it may apply to (OpenAirDocs) Matched by airframe and engine model; the AD's applicability may narrow it by serial number, part number or equipment. - Aircraft: 951 (951 by airframe model, 0 by engine model) - Makers: Airbus Helicopters 362, Eurocopter 328, American Eurocopter 162, Aerospatiale 66, Eurocopter France 20, S N I A S 8, Eurocopter/France 4, Airbus Helicopter 1 Models with the most aircraft: - [Airbus Helicopters AS350B3](https://openairdocs.org/model/airbus-helicopters-as350b3): 291 aircraft (airframe model) - [Eurocopter AS 350 B3](https://openairdocs.org/model/eurocopter-as-350-b3): 167 aircraft (airframe model) - [Eurocopter AS 350 B2](https://openairdocs.org/model/eurocopter-as-350-b2): 146 aircraft (airframe model) - [American Eurocopter AS350B3](https://openairdocs.org/model/american-eurocopter-as350b3): 124 aircraft (airframe model) - [Airbus Helicopters AS 350B3](https://openairdocs.org/model/airbus-helicopters-as-350b3): 56 aircraft (airframe model) - [American Eurocopter AS350B2](https://openairdocs.org/model/american-eurocopter-as350b2): 38 aircraft (airframe model) - [Aerospatiale AS350BA](https://openairdocs.org/model/aerospatiale-as350ba): 18 aircraft (airframe model) - [Aerospatiale AS350B](https://openairdocs.org/model/aerospatiale-as350b): 13 aircraft (airframe model) - [Eurocopter AS 350 BA](https://openairdocs.org/model/eurocopter-as-350-ba): 13 aircraft (airframe model) - [Aerospatiale AS350B2](https://openairdocs.org/model/aerospatiale-as350b2): 11 aircraft (airframe model) - [Airbus Helicopters AS350B2](https://openairdocs.org/model/airbus-helicopters-as350b2): 10 aircraft (airframe model) - [Aerospatiale AS 355F1](https://openairdocs.org/model/aerospatiale-as-355f1): 9 aircraft (airframe model) - [Eurocopter France AS 350 B3](https://openairdocs.org/model/eurocopter-france-as-350-b3): 8 aircraft (airframe model) - [Eurocopter France AS350B2](https://openairdocs.org/model/eurocopter-france-as350b2): 8 aircraft (airframe model) - [Aerospatiale AS 355F2](https://openairdocs.org/model/aerospatiale-as-355f2): 6 aircraft (airframe model) - [S N I A S AS-350B ECUREUIL](https://openairdocs.org/model/s-n-i-a-s-as-350b-ecureuil): 5 aircraft (airframe model) - [Eurocopter/France AS355N TWINSTAR](https://openairdocs.org/model/eurocopter-france-as355n-twinstar): 4 aircraft (airframe model) - [Aerospatiale AS355F2 ECUREUIL](https://openairdocs.org/model/aerospatiale-as355f2-ecureuil): 3 aircraft (airframe model) - [Airbus Helicopters AS350BA](https://openairdocs.org/model/airbus-helicopters-as350ba): 2 aircraft (airframe model) - [Airbus Helicopters AS355N](https://openairdocs.org/model/airbus-helicopters-as355n): 2 aircraft (airframe model) All 36 models: https://openairdocs.org/ad/2001-04-14/models.md Every aircraft: https://openairdocs.org/ad/2001-04-14/aircraft.md ## Related documents - [AD 85-14-06 R1](https://openairdocs.org/ad/85-14-06-R1) (historical): Fuselage Tailboom Interface · Eurocopter France AS-350B, AS-350B1, AS-350B2 and 10 more. Effective Sep 12, 1985. Replaced by this AD - [Proposed rule 2000-SW-17-AD](https://openairdocs.org/proposed/2000-SW-17-AD): Notice of proposed rulemaking (NPRM), published Dec 8, 2000 Its text cites no advisory circulars or STCs. ## NTSB investigations that cite this AD (1) From the NTSB's public API. Aircraft are matched to registry aircraft by N-number and event date, checked against the reported serial number, make and model; the registry's history has gaps, so older matches can be wrong. Compare the reported make and model. - [NTSB WPR12FA282](https://openairdocs.org/ntsb/WPR12FA282), Jun 30, 2012: Aerospatiale AS350B (N729DP), Camp Verde, AZ, substantial damage, 4 fatal. Probable cause: The pilot's improper decision to fly at a low altitude through a river canyon, contrary to voluntary guidance within the Special Conservation Area, which led to collision with a cable. 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