{"id":"F2006B10837","name":"AD/INST/34 - Honeywell SP-300 DFCS Mode Control Panel","slug":"ad-inst-34-honeywell-sp-300-dfcs-mode-control-panel","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"repealed","isInForce":false,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":56319,"registerId":"commonwealth-F2006B10837-current","compilationNumber":null,"startDate":"2026-04-02","status":"Repealed","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/INST/34 - Honeywell SP-300 DFCS Mode Control Panel","content":"---\nmeta-content-style-type: text/css\nmeta-content-type: application/xhtml+xml; charset=utf-8\nmeta-generator: Aspose.Words for .NET 22.10.0\n---\n\n?xml version=\"1.0\" encoding=\"utf-8\" standalone=\"no\"?>\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 107 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n \n\n![](image.001.png)  Instruments and Automatic Pilots\n\n \n\nAD/INST/34 Honeywell SP-300 DFCS Mode Control Panel 11/88\n\nApplicability: Honeywell (Sperry) Digital Flight Control System SP-300 mode control panel P/Ns 4051601-915 and 4051601-916.\n\n \n\nRequirement: Action in accordance with Honeywell Alert SB 21A-1142-16. Compliance:  Prior to 30 June 1989.\n\nBackground:  During operations in severe EMI environment, unselected changes in the altitude window setting may occur. This modification reduces the possibility of such altitude changes.\n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n\n \n","sortOrder":0}],"analysis":{"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive's scope, as expressed in the text provided, is unchanged from its stated original aim: it applies only to Honeywell (Sperry) SP-300 mode control panels P/Ns 4051601-915 and 4051601-916 and requires the modification described in Honeywell Alert SB 21A-1142-16 to reduce unselected altitude window changes that may occur in severe EMI environments. The instrument prescribes the action and a compliance date; there is no indication in the supplied text that the applicable equipment, required action, or stated purpose have been expanded or narrowed from what the directive records. (Applicability, Requirement, Compliance, Background)"},"complexity_factors":["Narrow technical applicability to two specific part numbers (4051601-915 and 4051601-916). (Applicability)","Reliance on an external technical document (Honeywell Alert SB 21A-1142-16) for the detailed modification steps. (Requirement)","Safety-critical system context (flight control panel) increases practical implementation demands despite simple directive text. (Background)","Fixed compliance deadline requiring scheduling of maintenance and potential aircraft downtime. (Compliance)","Limited administrative discretion in the directive (mandatory action and deadline), though contractors/maintenance providers make implementation choices. (Requirement, Compliance)"],"plain_english_summary":"Owners/operators must have Honeywell (Sperry) SP-300 DFCS mode control panels (PN 4051601-915 and -916) modified per Honeywell Alert SB 21A-1142-16 by 30 June 1989 to reduce the risk of uncommanded altitude changes in severe EMI. Operators bear costs and arrange qualified maintenance to perform the bulletin’s instructions; the AD fixes the deadline and leaves technical execution to certificated or authorised providers."},"kimi_summary":{"_metrics":{"model":"kimi-k2.5","source":"moonshot-batch","completionTokens":1584},"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"The directive maintains its original targeted scope addressing only the specific Honeywell SP-300 Mode Control Panel models susceptible to EMI-induced altitude window changes. It has not expanded beyond this specific avionics safety issue."},"complexity_factors":["Extremely narrow scope limited to two specific part numbers (4051601-915 and 4051601-916)","Single, unambiguous requirement referencing an external technical standard","No definitions section, exceptions, or conditional provisions","Clear, absolute compliance deadline with no staging or alternative compliance methods"],"plain_english_summary":"**What it does:** This is a mandatory safety fix for specific Honeywell flight control computers used in aircraft. It requires owners or operators to modify certain \"Mode Control Panels\" (the interface pilots use to input altitude and other flight settings) to prevent the altitude setting from changing unexpectedly.\n\n**Who it affects:** Anyone operating aircraft fitted with Honeywell SP-300 Digital Flight Control System panels with part numbers 4051601-915 or 4051601-916.\n\n**Why it matters:** In areas with strong electromagnetic interference (EMI)—such as near radar stations or powerful radio transmitters—these panels could glitch and change the target altitude without the pilot touching the controls. This creates a serious risk of sudden altitude deviations that could lead to mid-air collisions or controlled flight into terrain. The directive mandates a hardware or software update (detailed in Honeywell Service Bulletin 21A-1142-16) to eliminate this vulnerability.\n\n**Key requirement:** The modification had to be completed before 30 June 1989."},"summary":{"content_quality":"ok","complexity_score":1,"scope_assessment":{"changed":false,"description":"This is an airworthiness directive issued under regulation 39 of the Civil Aviation Regulations 1998. It imposes a mandatory modification requirement on affected aircraft operators but does not amend the regulations themselves."},"complexity_factors":["The directive references a single external manufacturer service bulletin for the required modification action.","It applies only to two specific part numbers of a single model of mode control panel.","It has a single, past-due compliance deadline with no repetitive actions or alternative methods of compliance."],"plain_english_summary":"This is an airworthiness directive (AD) issued by the Civil Aviation Safety Authority under Part 39 of the Civil Aviation Regulations 1998. It applies to the Honeywell (formerly Sperry) SP-300 Digital Flight Control System mode control panel, specifically part numbers 4051601-915 and 4051601-916. The AD addresses a problem observed during operations in severe electromagnetic interference (EMI) environments: unselected changes to the altitude window setting could occur, causing a risk of unintended altitude selections. To reduce that risk, the directive requires a modification to the affected mode control panels. The modification must be carried out in accordance with Honeywell Alert Service Bulletin 21A-1142-16. The compliance deadline set by the AD was before 30 June 1989.\n\nIf you operate or maintain an aircraft fitted with one of these specific Honeywell SP-300 mode control panels, this directive is relevant to you. The practical point is safety: ensuring altitude setting integrity when exposed to EMI. The directive is a mandatory continuing airworthiness requirement, and even though the deadline has passed, any aircraft that did not complete the modification should be assessed for compliance. The AD does not introduce new regulations; it simply enforces a technical fix via an existing service bulletin."}},"importantCases":[],"_links":{"self":"/api/acts/ad-inst-34-honeywell-sp-300-dfcs-mode-control-panel","history":"/api/acts/ad-inst-34-honeywell-sp-300-dfcs-mode-control-panel/history","analysis":"/api/acts/ad-inst-34-honeywell-sp-300-dfcs-mode-control-panel/analysis","conflicts":"/api/acts/ad-inst-34-honeywell-sp-300-dfcs-mode-control-panel/conflicts","importantCases":"/api/acts/ad-inst-34-honeywell-sp-300-dfcs-mode-control-panel/important-cases","documents":"/api/acts/ad-inst-34-honeywell-sp-300-dfcs-mode-control-panel/documents"}}