{"id":"F2006B09812","name":"AD/F28/78 - Lap Joint at Stringer 16/17 and 58/59","slug":"ad-f28-78-lap-joint-at-stringer-16-17-and-58-59","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":54737,"registerId":"commonwealth-F2006B09812-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/F28/78 - Lap Joint at Stringer 16/17 and 58/59","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)  \nFokker F28 Series Aeroplanes\n\nAD/F28/78 Lap Joint at Stringer 16/17 and 58/59 11/96\n\nApplicability: Models F28 Mk. 1000 through to 4000 Series, S/Nos. 11017 to 11241 that do not have SB F28/53-121 incorporated.\n\nRequirement: Action in accordance with Fokker SB F28/53-144.\n\nNote: RLD AD 1996-081(A) refers.\n\nCompliance: Unless already accomplished; on aircraft that have accumulated between:\n\n    25 000 and 32 000 flight cycles at 01 July 1996 \\- before 10 December 1996;\n\n    b. 20 000 and 25 000 flight cycles at 01 July 1996 \\- before 10 January 1997; and\n\n    c. 15 000 and 20 000 flight cycles at 01 July 1996 \\- before 10 February 1997\\. This Directive has effect from 10 October 1996.\n\nBackground: Cracking has been discovered in these lap joints before the inspection threshold mandated in the Structural Integrity Programme, and before the cycles threshold of AD/F28/75. This Directive requires a one time inspection of the area using the existing LFEC technique and if cracking is found, installation of a terminating repair.","sortOrder":0}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":3,"scope_assessment":{"changed":false,"description":"This Airworthiness Directive maintains its original narrow scope: a targeted safety inspection for a specific structural issue on a specific aircraft type. It does not expand beyond its original purpose of addressing premature cracking in Fokker F28 lap joints."},"complexity_factors":["Multiple applicability conditions (specific model range, serial number range, exclusion for aircraft with prior modification)","Tiered compliance deadlines based on flight cycle thresholds (three separate brackets)","Technical aviation terminology requiring specialized knowledge (lap joints, stringers, flight cycles, LFEC technique, terminating repair)","Reference to external technical documents (Fokker Service Bulletin F28/53-144 and referenced AD/F28/75) without reproducing their content","Cross-reference to Dutch aviation authority directive (RLD AD 1996-081(A))"],"plain_english_summary":"This safety order requires a one-time inspection of specific fuselage lap joints on Fokker F28 Mk.1000–4000 series (S/N 11017–11241) that haven’t had SB F28/53-121, using Fokker Service Bulletin F28/53-144. If cracks are found, a terminating repair must be installed. Compliance deadlines vary by flight-cycle band as of 1 July 1996. It’s a preemptive safety action after cracks appeared earlier than expected to prevent structural failure."},"flash_summary":{"complexity_score":4,"scope_assessment":{"changed":true,"description":"This Directive brings forward inspection action relative to the previously mandated Structural Integrity Programme and the cycle threshold in AD/F28/75 by requiring an earlier, one‑time LFEC inspection and potential repair for the defined subset of aircraft (those within S/N 11017–11241 that lack SB F28/53‑121), with compliance deadlines tied to flight cycles as at 1 July 1996."},"complexity_factors":["Targeted applicability: limited to specific models and serial numbers and only aircraft without SB F28/53‑121 incorporated","Multiple compliance windows tied to flight‑cycle brackets as at a fixed date (1 July 1996) with different cut‑off dates","Dependence on an external service bulletin (Fokker SB F28/53‑144) for inspection and repair procedures","Specified inspection technique (LFEC) and a conditional terminating repair if cracking is found","Cross‑reference to another authority directive (RLD AD 1996‑081(A))"],"plain_english_summary":"This Airworthiness Directive requires a one‑time, non‑destructive (LFEC) inspection of specific lap joints on selected Fokker F28 Mk.1000–4000 aeroplanes (S/N 11017–11241) that have not had Service Bulletin F28/53‑121 fitted, and mandates installing a terminating repair if cracking is found. Compliance deadlines are set by each aircraft's flight‑cycle count as at 1 July 1996 and follow the procedures in Fokker SB F28/53‑144. Operators must arrange and pay for the inspections and any repairs by the specified dates."}},"importantCases":[],"_links":{"self":"/api/acts/ad-f28-78-lap-joint-at-stringer-16-17-and-58-59","history":"/api/acts/ad-f28-78-lap-joint-at-stringer-16-17-and-58-59/history","analysis":"/api/acts/ad-f28-78-lap-joint-at-stringer-16-17-and-58-59/analysis","conflicts":"/api/acts/ad-f28-78-lap-joint-at-stringer-16-17-and-58-59/conflicts","importantCases":"/api/acts/ad-f28-78-lap-joint-at-stringer-16-17-and-58-59/important-cases","documents":"/api/acts/ad-f28-78-lap-joint-at-stringer-16-17-and-58-59/documents"}}