{"id":"F2006B02617","name":"AD/B717/2 - Loss of Altitude Information","slug":"ad-b717-2-loss-of-altitude-information","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":41933,"registerId":"commonwealth-F2006B02617-current","compilationNumber":null,"startDate":"2026-04-01","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"AIRWORTHINESS DIRECTIVE","sectionType":"part","heading":"AIRWORTHINESS DIRECTIVE","content":"# AIRWORTHINESS DIRECTIVE\n\n![](image.002.png) ![](image.003.png)\n\n![](image.002.png)  \nFor the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CAR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.","sortOrder":0},{"sectionNumber":"AD/B717/2 Loss of Altitude Information 5","sectionType":"part","heading":"AD/B717/2 Loss of Altitude Information 5/2001 TX","content":"# AD/B717/2 Loss of Altitude Information 5/2001 TX\n\nApplicability: All Model 717-200 series aeroplanes.\n\nRequirement: 1. If not previously accomplished, coil and stow the electrical wires between the glareshield control panel and the Integrated Standby Instrument System in accordance with Boeing alert Service Bulletin 717-34A0002 dated 30 March 2000.\n\n2. If not previously accomplished, revise the Abnormal Procedures Section of the Aircraft Flight Manual (AFM) to include procedures for identifying and pulling certain circuit breakers. This must be accomplished by inserting Boeing Interim Operating Procedure 2-17, dated 31 March 2000, or Boeing Interim Operating Procedures 2-17A, dated 16 August 2000 into the AFM.\n\nNote: FAA AD 2000-07-51 Amdt 39-11713 refers.\n\nCompliance: For Requirement 1 – Before further flight after the effective date of this Directive. For Requirement 2 – Before further flight after the effective date of this Directive. This Airworthiness Directive becomes effective on 26 March 2001.\n\nBackground: The FAA received a report of two incidents in which an intermittent loss of altitude data occurred simultaneously on the Captain’s Primary Flight Display (PFD), First Officer’s PFD, and the Integrated Standby Instrument System (ISIS) altitude display due to a voltage drop in the power distribution control unit. Additional intermittent loss of cockpit indications included the glareshield control panel data, navigation data, flight management computer mismatch annunciation, autopilot disconnect, and autothrottle disconnect. In both cases, the airspeed and attitude indication remained operational and the flights continued to their destination without further incident.","sortOrder":1}],"analysis":{"flash_summary":{"complexity_score":2,"scope_assessment":{"changed":false,"description":"This Directive remains narrowly focused on addressing the specific failure mode reported (intermittent loss of altitude information due to a voltage drop affecting multiple displays). The actions required (wire stow and AFM abnormal procedures insertion) align directly with that original safety purpose and do not expand scope beyond the initial technical and procedural mitigations."},"complexity_factors":["Short document with two discrete mandatory actions (Requirement 1 and Requirement 2)","Single applicability class: all Model 717-200 series","Compliance timing is simple and unconditional: 'Before further flight after the effective date'","References to external documents (Boeing Alert Service Bulletin 717-34A0002; Boeing Interim Operating Procedures 2-17 / 2-17A) but no internal definitions or cross-referencing complexity","One background incident description explaining the safety motivation","No nested exceptions, conditional pathways, or multiple compliance options in the Directive text"],"plain_english_summary":"**What this directive does (mechanically)**\n\n- Applies to: all Boeing 717-200 aeroplanes.\n- Requires two actions to be completed before the aeroplane’s next flight after the Directive becomes effective:\n  1. Physically coil and stow the electrical wires between the glareshield control panel and the Integrated Standby Instrument System (ISIS) following Boeing Alert Service Bulletin 717-34A0002 (30 March 2000).  \n  2. Update the Aircraft Flight Manual (AFM) Abnormal Procedures section by inserting Boeing Interim Operating Procedure 2-17 (31 March 2000) or 2-17A (16 August 2000). That procedure describes how to identify and pull certain circuit breakers if the fault occurs.\n\n**Who is affected**\n\n- Aircraft operators/owners of Boeing 717-200s: they must arrange and pay for the wiring work and the AFM update.\n- Maintenance organisations and licensed engineers: they perform the wiring stow work to the service bulletin standard.\n- Flight crews: they must follow the newly inserted abnormal procedures (AFM revision) if the indicated failure occurs.\n\n**Why it matters (official rationale)**\n\n- The FAA reported two occurrences where an intermittent voltage drop in a power distribution control unit caused simultaneous loss of altitude information on both pilots’ Primary Flight Displays and the ISIS altitude readout. Other cockpit indications were also affected intermittently. Although airspeed and attitude remained available and the flights continued safely, losing altitude information on multiple displays creates a safety risk the Directive aims to remove.\n\n**How the measures address the problem**\n\n- Coiling and stowing the wires reduces the likelihood of chafing, unwanted contact or wiring-induced faults that could contribute to intermittent power/voltage issues between the glareshield control panel and ISIS (mechanical mitigation).  \n- The AFM change provides an immediate operational mitigation (procedural response) so crews can isolate the fault quickly by pulling specified circuit breakers, restoring affected systems or preventing further effects.\n\n**Costs, incentives and trade-offs**\n\n- Who pays: aircraft operators/owners pay for the physical work and the AFM administrative update. If carried out during scheduled maintenance the direct flight downtime cost is small; if done as an out-of-cycle task it may cause some short-term aircraft unavailability.\n- Implementation cost: modest labour and record-keeping; no special hardware is mandated beyond correct wire stowing per the Service Bulletin.\n- Behavioural change: maintenance teams must perform the wire stow and log compliance; flight crews must be trained or briefed on the inserted AFM abnormal procedure.\n- Trade-offs: instructing crews to pull circuit breakers can restore or isolate systems quickly, but pulling breakers may also remove other functions powered through the same circuit. Operators must understand the precise systems affected by those breakers (the AFM/IOP should specify this) so crews do not inadvertently remove critical capability.\n\n**Compliance, risks and unintended consequences**\n\n- Compliance is time-critical (required before next flight). That compresses scheduling but reduces exposure to the risk.\n- Implementation risk is moderate: the wiring change is straightforward for qualified maintenance staff, but if not installed exactly as the service bulletin requires the mitigation may be less effective.\n- Potential unintended consequences: incorrect pulling of circuit breakers could disable unrelated systems or lead to confusion in high-workload situations; improper stowage that does not follow the service bulletin could leave the underlying vulnerability unaddressed.\n\n**Net distribution of effects**\n\n- Concentrated benefits accrue to crews, passengers and the operator through reduced risk of simultaneous altitude-data loss.  \n- Concentrated costs fall on aircraft operators (maintenance time, labour, record updates).  \n\n(Referenced provisions: Requirement 1 and Requirement 2; Background incident description.)"},"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"},"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This AD maintains its original narrow scope — addressing a specific electrical fault on a specific aircraft type. The requirements remain tightly focused on the identified unsafe condition (loss of altitude information due to voltage drop) without expanding into unrelated systems or operational areas."},"complexity_factors":["Very short document (approximately 300 words)","Only 2 substantive requirements with clear, sequential numbering","Minimal defined terms (only standard aviation acronyms: PFD, ISIS, AFM)","No nested exceptions or conditional logic beyond simple 'if not previously accomplished' clauses","Single cross-reference to FAA AD 2000-07-51 for background context only","Clear compliance dates with no alternative methods or escalations","Straightforward applicability (all aircraft of one specific model series)"],"plain_english_summary":"This CASA Airworthiness Directive mandates that Boeing 717‑200 operators fix an electrical wiring fault and insert a new emergency procedure in the Aircraft Flight Manual. The action responds to an FAA finding that a voltage drop can make multiple cockpit displays (including primary and standby altitude) go blank, risking loss of altitude data, navigation, autopilot and autothrottle. Both remedies must be done before the aircraft’s next flight after 26 March 2001."}},"importantCases":[],"_links":{"self":"/api/acts/ad-b717-2-loss-of-altitude-information","history":"/api/acts/ad-b717-2-loss-of-altitude-information/history","analysis":"/api/acts/ad-b717-2-loss-of-altitude-information/analysis","conflicts":"/api/acts/ad-b717-2-loss-of-altitude-information/conflicts","importantCases":"/api/acts/ad-b717-2-loss-of-altitude-information/important-cases","documents":"/api/acts/ad-b717-2-loss-of-altitude-information/documents"}}