{"id":"F2006B03076","name":"AD/B747/174 Amdt 1 - Strut Midspar Fitting Lower Horizontal Clevis","slug":"ad-b747-174-amdt-1-strut-midspar-fitting-lower-horizontal-clevis","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":42435,"registerId":"commonwealth-F2006B03076-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/B747/174 Amdt 1 - Strut Midspar Fitting Lower Horizontal Clevis","content":"COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n![](image.001.png)  \nBoeing 747 Series Aeroplanes\n\nAD/B747/174\n\nAmdt 1\n\n  \nStrut Midspar Fitting Lower Horizontal Clevis 10/97\n\nApplicability: Model 747 series aircraft with line numbers 1 through 886; equipped with Pratt and Whitney JT9D-3, -7, and -70 series engines, General Electric CF6-45/-50 series engines, or Rolls Royce RB211 series engines; and on which the strut/wing modification has not been accomplished in accordance with Boeing Alert Service Bulletin (ASB) 747-54A2157, Boeing ASB 54A2158, or Boeing ASB 747-54A2159,\n\nas applicable.\n\nRequirement: Action in accordance with the technical requirements of FAA AD 97-12-03 Amdt 39- 10045.\n\nNote: Boeing Alert Service Bulletins 747-54A2179 and 747-54A2179 Revision 1, and Boeing Service Bulletin 747-54-2118 and subsequent revisions refer.\n\nCompliance: As specified in the requirement document with a revised effective date of 11 September 1997.\n\nBackground: The FAA received reports of fatigue cracking, stress corrosion cracking, and fracturing of the horizontal clevis of the inboard midspar fitting at the number 3 strut position. Such cracking and fracturing could result in drooping of the strut at the strut-to-wing interface, and consequent separation of the engine and strut from the aircraft.\n\nAmendment 1 is issued in response to a new FAA AD which combines the requirements of FAA ADs 87-04-13 R1 (AD/B747/57 Amdt 1) and 96-25-01 in this directive. This amendment continues to require inspections to detect cracking, corrosion, and fracturing of the lower horizontal clevis; and adds corresponding inspections of the upper horizontal clevis, and replacement of discrepant parts with new parts, or rework, if necessary. This amendment also removes certain optional terminating actions. This latest FAA action is prompted by reports of cracking of the lower and upper leg of the horizontal clevis of the midspar fitting.\n\nThe original issue of this airworthiness directive became effective on 24 April 1997.","sortOrder":0}],"analysis":{"flash_summary_failed":{"failed":true,"reason":"A positive credit balance is required for all requests, including BYOK, so fallback providers remain available. Add credits at https://vercel.com/d?to=%2F%5Bteam%5D%2F%7E%2Fai%3Fmodal%3Dtop-up to continue.","source":"analysis-cron"},"flash_summary":{"complexity_score":6,"scope_assessment":{"changed":true,"description":"Amendment 1 expands and reshapes the original directive: it continues required inspections of the lower horizontal clevis and adds corresponding inspections of the upper horizontal clevis, mandates replacement or rework of discrepant parts, removes certain optional terminating actions, and consolidates requirements of earlier FAA ADs (see 'Amendment 1' and 'Background')."},"complexity_factors":["Conditional applicability: limited to Model 747 line numbers 1–886 with specified engine types and only where certain Boeing strut/wing modifications have not been done (see 'Applicability').","Cross‑jurisdictional reliance: requires action 'in accordance with the technical requirements of FAA AD 97‑12‑03' rather than reproducing requirements locally ('Requirement').","Multiple referenced service bulletins: note and related Boeing ASBs and Service Bulletins are cited as guidance (see 'Note').","Technical inspection and corrective-action obligations: inspections for fatigue cracking, stress corrosion cracking and fracturing, plus mandated replacement or rework of discrepant parts ('Background' and 'Amendment 1' summary).","Amendment complexity: combines prior ADs and changes scope (adds upper clevis inspections, removes certain optional terminating actions), creating tracing requirements to earlier directives ('Amendment 1' paragraph).","Compliance timing: specifies compliance 'as specified in the requirement document with a revised effective date of 11 September 1997', adding an external timing dependency ('Compliance').","Operational risk linkage: the directive addresses a high‑consequence failure mode (engine/strut separation) which raises urgency and potential operational disruption ('Background')."],"plain_english_summary":"**What it does:** Requires operators of specified Boeing 747s (line numbers 1–886) with JT9D, CF6 or RB211 engines, and without certain Boeing strut/wing modifications, to carry out inspections and, if necessary, rework or replace the midspar fitting horizontal clevis parts in accordance with FAA AD 97‑12‑03.  \n\n**Why it matters:** The inspections target cracking, corrosion and fracture of the lower and upper horizontal clevis to prevent strut droop and possible engine/strut separation; operators bear the cost and operational burden of inspections, repairs and replacements."},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":true,"description":"The original directive (effective April 1997) only required inspections of the lower horizontal clevis. Amendment 1 expands the scope significantly: it adds inspections of the upper horizontal clevis, mandates replacement/rework of discrepant parts, and removes certain optional terminating actions. The amendment also consolidates requirements from two separate prior FAA directives (87-04-13 R1 and 96-25-01) into this single directive, making it more comprehensive than the original issue."},"complexity_factors":["Multiple cross-references to external documents (FAA AD 97-12-03, Boeing Alert Service Bulletins 747-54A2157/2158/2159/2179, Boeing Service Bulletin 747-54-2118)","Precise applicability criteria combining four conditions (line numbers, engine types, modification status)","Technical aviation terminology requiring specialist knowledge (\"strut midspar fitting\", \"horizontal clevis\", \"terminating actions\")","Amendment structure referencing prior versions and consolidating two previous FAA directives","Conditional logic in applicability (\"as applicable\", \"has not been accomplished\")"],"plain_english_summary":"This FAA airworthiness directive mandates immediate inspections and—if needed—repair or replacement of the strut midspar fitting horizontal clevis (lower, and by this amendment also the upper) on certain Boeing 747s (S/N 1–886) with specified Pratt & Whitney, GE, or Rolls‑Royce engines, unless the strut/wing modification was done. Inspections target fatigue cracking, stress corrosion, and fractures to prevent engine‑strut droop or separation. Operators must follow FAA AD 97‑12‑03; effective 11 September 1997."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b747-174-amdt-1-strut-midspar-fitting-lower-horizontal-clevis","history":"/api/acts/ad-b747-174-amdt-1-strut-midspar-fitting-lower-horizontal-clevis/history","analysis":"/api/acts/ad-b747-174-amdt-1-strut-midspar-fitting-lower-horizontal-clevis/analysis","conflicts":"/api/acts/ad-b747-174-amdt-1-strut-midspar-fitting-lower-horizontal-clevis/conflicts","importantCases":"/api/acts/ad-b747-174-amdt-1-strut-midspar-fitting-lower-horizontal-clevis/important-cases","documents":"/api/acts/ad-b747-174-amdt-1-strut-midspar-fitting-lower-horizontal-clevis/documents"}}