{"id":"F2009L00886","name":"AD/ERJ-170/21 - Outboard Slat Skew Sensor","slug":"ad-erj-170-21-outboard-slat-skew-sensor","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":78183,"registerId":"commonwealth-F2009L00886-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"Embraer ERJ-170 Series Aeroplanes","sectionType":"division","heading":"Embraer ERJ-170 Series Aeroplanes","content":"### Embraer ERJ-170 Series Aeroplanes\n\n| AD/ERJ-170/21 | Outboard Slat Skew Sensor | 4/2009 |\n| ------------- | ------------------------- | ------ |\n\n| Applicability: | Model ERJ 170-100 STD, ERJ 170-100 LR, ERJ 170-100 SU, ERJ 170-100 SE,ERJ 170-200 STD, ERJ 170-200 SU and ERJ 170-200 LR aircraft, equipped with the outboard slat skew sensor part number 1702286A or 1702288A.                                                                                 |\n| -------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ |\n| Requirement:   | Action in accordance with the requirements of ANAC AD 2009-02-02 Amdt39-1260.If an outboard slat skew sensor is found to be unserviceable, before further flight, replace it with a serviceable sensor.                                                                                          |\n| Compliance:    | Within 1,320 flight hours after 9 April 2009, unless already accomplished. Repeat thereafter at intervals not to exceed 1,320 flight hours.                                                                                                                                                      |\n|                | This Airworthiness Directive becomes effective on 9 April 2009.                                                                                                                                                                                                                                  |\n| Background:    | There has been an occurrence of outboard slat skew sensor failure. In combination with other possible faults, this may result in slat surface detachment from the wing, with the possibility of damage to the horizontal stabiliser and elevator, and could result in a loss of controllability. |\n\n![](image.001.png)  \nDavid Villiers  \nDelegate of the Civil Aviation Safety Authority\n\n24 February 2009","sortOrder":0},{"sectionNumber":"AD/ERJ-170/21","sectionType":"part","heading":"AD/ERJ-170/21","content":"## AD/ERJ-170/21","sortOrder":1},{"sectionNumber":"Outboard Slat Skew Sensor","sectionType":"part","heading":"Outboard Slat Skew Sensor","content":"## Outboard Slat Skew Sensor","sortOrder":2},{"sectionNumber":"4/2009","sectionType":"part","heading":"4/2009","content":"## 4/2009","sortOrder":3}],"analysis":{"kimi_summary":{"content_quality":"ok","complexity_score":2,"scope_assessment":{"changed":false,"description":"This is a standard, targeted airworthiness directive addressing a specific safety-critical component failure. The scope remains precisely limited to the identified sensor issue on the specified aircraft models, consistent with the original purpose of preventing slat detachment."},"complexity_factors":["Single, specific mechanical component targeted (outboard slat skew sensor)","Only two part numbers affected","Straightforward compliance requirement: inspect/replace on failure","Simple recurring interval (1,320 flight hours)","No nested exceptions, conditional logic, or extensive cross-referencing","Refers to one external document (ANAC AD 2009-02-02) for technical details rather than reproducing them","Total length: approximately 200 words of substantive content"],"plain_english_summary":"This AD requires operators of Embraer ERJ‑170 aircraft with specific outboard slat skew sensor part numbers to inspect those sensors and replace any broken unit before next flight. \n\nIt responds to an incident and addresses the risk that a failed sensor, combined with other faults, could allow a slat to detach in flight, damage the tail, and threaten control. Inspections begin within 1,320 flight hours after 9 April 2009 and repeat every 1,320 hours."},"flash_summary":{"complexity_score":3,"scope_assessment":{"changed":false,"description":"The directive adopts the ANAC AD requirements and confines action to the listed ERJ‑170 models fitted with the two specified sensor part numbers. It mandates replacement of unserviceable sensors and recurring compliance at 1,320 flight‑hour intervals; no broadened or narrowed scope beyond those elements is indicated in the text provided."},"complexity_factors":["Narrow applicability limited to listed ERJ‑170 variants and two specific sensor part numbers (Applicability)","Single, clear mandated action: replace unserviceable sensor before further flight (Requirement)","Recurring compliance interval (repeat every 1,320 flight hours) creates ongoing operational scheduling and maintenance burden (Compliance)","Directly adopts requirements of a foreign authority's AD (ANAC AD 2009-02-02 Amdt39-1260), requiring operators to follow external mandated procedures (Requirement)","Safety consequence described as severe (slat detachment, possible loss of control), but mitigation is straightforward and prescriptive (Background)","Administrative elements: effective date, mandatory nature, and recordkeeping/implementation by operators increase operational compliance tasks (Compliance; Effective date)"],"plain_english_summary":"This Airworthiness Directive requires operators of specified Embraer ERJ‑170 models fitted with outboard slat skew sensors part numbers 1702286A or 1702288A to replace any unserviceable sensor before further flight and to repeat the action at intervals not exceeding 1,320 flight hours (Requirement; Compliance). It responds to reported sensor failures that, in combination with other faults, could allow slat detachment and possible loss of control (Background); operators pay for replacements and must comply from 9 April 2009."},"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"}},"importantCases":[],"_links":{"self":"/api/acts/ad-erj-170-21-outboard-slat-skew-sensor","history":"/api/acts/ad-erj-170-21-outboard-slat-skew-sensor/history","analysis":"/api/acts/ad-erj-170-21-outboard-slat-skew-sensor/analysis","conflicts":"/api/acts/ad-erj-170-21-outboard-slat-skew-sensor/conflicts","importantCases":"/api/acts/ad-erj-170-21-outboard-slat-skew-sensor/important-cases","documents":"/api/acts/ad-erj-170-21-outboard-slat-skew-sensor/documents"}}