{"id":"F2006B04990","name":"AD/CESSNA 170/61 - Alternate Static Source Valve Inspection","slug":"ad-cessna-170-61-alternate-static-source-valve-inspection","collection":"legislative_instrument","jurisdiction":"commonwealth","status":"in_force","isInForce":true,"actNumber":null,"makingDate":null,"administeringDepartment":null,"currentVersion":{"id":44887,"registerId":"commonwealth-F2006B04990-current","compilationNumber":null,"startDate":"2026-04-02","status":"InForce","reasons":null,"registeredAt":null},"sections":[{"sectionNumber":"1","sectionType":"section","heading":"AD/CESSNA 170/61 - Alternate Static Source Valve Inspection","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)  \nCessna 170, 172, F172, FR172 and 175 Series Aeroplanes\n\nAD/CESSNA 170/61 Alternate Static Source Valve Inspection 3/98 DM\n\nApplicability: All Cessna Model 172R Aircraft with the following serial numbers: 17280003 through 17280171 inclusive;\n\n17280173 through 17280175 inclusive;\n\n17280177 through 17280179 inclusive;\n\n17280182 through 17280184 inclusive;\n\n17280186, 17280189, 17280190, 17280192 through 17280212 inclusive;\n\n17280214, 17280216 through 17280221 inclusive;\n\n17280214, 17280216 through 17280221 inclusive;\n\n17280223 through 17280236 inclusive;\n\n17280239 through 17280251 inclusive;\n\n17280253 through 17280263 inclusive;\n\n17280265, 17280268, 17280270 through 17280272 inclusive; and\n\n17280283, 17280297, and 17280301 inclusive.\n\nRequirement: 1. Fabricate placards with the following words, using letters at least 3mm (1/8-inch) in height, and install these placards in the cockpit within the pilot's clear view:\n\n    'IFR operation is prohibited.'\n\n    b. 'Use of the alternate static air source is prohibited.'\n\n    2. Inspect the alternate static air source valve to assure that the alternate static air source valve is not restricted by the identification placard and to assure that the valve body does not separate from the valve flange in accordance with Cessna Service Bulletin No. SB97-34-02, Revision 1, dated December 22, 1997.\n\n    3. If the alternate static air source valve is restricted, rework the alternate static air source assembly in accordance with Cessna Service Bulletin No. SB97-34-02, Revision 1, dated December 22, 1997.\n\n    4. If the valve body separates from the valve flange, replace the alternate static air source assembly in accordance with the maintenance manual.\n\nNote: FAA Priority Letter AD 98-01-01.\n\nCompliance: 1. Prior to further flight, after the effective date of this AD.\n\nCOMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 \\- 105 CIVIL AVIATION SAFETY AUTHORITY\n\nSCHEDULE OF AIRWORTHINESS DIRECTIVES\n\n    2. Within the next 100 hours time-in-service (TIS) after the effective date of this AD or the 21st May 1998, whichever occurs first. Accomplishment of the applicable parts of Requirement 2 is terminating action for the placard requirements detailed in Paragraph 1 if no fault is found.\n\n    3. Prior to further flight after the inspection detailed by Requirement 2 of this AD. Rework of the alternate static air source assembly is terminating action for the placard requirements detailed in Paragraph 1.\n\n4: Either:\n\n    Prior to further flight to eliminate the operating limitations required by the placards in paragraph 1; or\n\n    b. Within the next 25 hours time in service after the inspection provided the operating limitations required by the placards in Paragraph 1 of this AD are adhered to.\n\nThis airworthiness directive becomes effective on 21 January 1998.\n\nBackground: The FAA has received reports from Cessna about the improper installation of the identification placard on the alternate static source. The placard was installed on the valve body in a location that covers the external orifice, which is the inlet for static air reference into the valve. If these assemblies are not corrected selection of alternate static air source will cause the altimeter, airspeed and vertical speed indicators to display erroneous indications.","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":5,"scope_assessment":{"changed":false,"description":"The directive applies to a defined set of Cessna 172R serial numbers and prescribes placarding, inspection, and corrective action consistent with the stated FAA reports and Cessna service bulletin. There is no indication within the text that the AD expands or narrows its original technical scope; it specifies interim operating limits and conditional terminating actions tied to inspection and repair."},"complexity_factors":["Narrow applicability by many specific serial numbers increases administrative tracking for operators.","Multiple compliance timeframes (prior to further flight, within 100 hours TIS or by 21 May 1998, and within 25 hours TIS) create staged obligations.","Actions combine simple placard work with technical inspection and possible rework or full replacement (different skill and parts requirements).","Terminating actions: successful inspection or rework removes placard restriction — creates conditional compliance logic.","Dependence on an external technical document (Cessna Service Bulletin SB97-34-02 Rev 1) and the maintenance manual for corrective steps.","Safety-critical nature: instrument errors (altimeter/airspeed/VSI) amplify enforcement and liability consequences.","Reference to FAA Priority Letter AD adds an external regulatory linkage to the directive's basis."],"plain_english_summary":"This airworthiness directive requires operators of specified Cessna 172R serial numbers to fit cockpit placards prohibiting IFR and use of the alternate static source, inspect the alternate static-air-source valve so the placard does not block the external static inlet and the valve body is secure, and to rework or replace the assembly per Cessna Service Bulletin SB97-34-02 Rev 1 or the maintenance manual. It matters because a blocked or separated valve can make the altimeter, airspeed and vertical-speed indicators display erroneous readings; compliance deadlines include immediate, 100‑hour and 25‑hour actions, imposing inspection and possible repair or parts costs."},"kimi_summary":{"content_quality":"ok","complexity_score":4,"scope_assessment":{"changed":false,"description":"This is a targeted safety directive addressing a specific manufacturing defect in a limited production run of aircraft. The scope remains precisely focused on the identified unsafe condition without expansion into broader operational or maintenance requirements."},"complexity_factors":["Multiple overlapping compliance deadlines (prior to further flight, 100 hours TIS, 25 hours TIS, fixed date of 21 May 1998)","Conditional logic: different actions required depending on inspection findings (restricted vs. separated valve body)","Terminating action provisions that modify other requirements based on outcomes","Extensive serial number list with unusual gaps and ranges (17280003-17280171, then 17280173-17280175, etc.)","Cross-reference to external technical document (Cessna Service Bulletin SB97-34-02 Revision 1)","Nested conditions in Requirement 4 (two alternative compliance paths with different prerequisites)","Duplicate serial number entry (17280214, 17280216-17280221 appears twice in the list)"],"plain_english_summary":"This CASA Airworthiness Directive requires owners/operators of specific Cessna 172R serials to address a misinstalled alternate static air source valve whose identification placard can block the inlet, causing false instrument readings. It mandates immediate cockpit warnings against IFR use of the alternate source, prompt inspection and repair or replacement of affected valves, and removal of warnings once corrected. It affects roughly 170 aircraft and prevents dangerous instrument errors in flight."}},"importantCases":[],"_links":{"self":"/api/acts/ad-cessna-170-61-alternate-static-source-valve-inspection","history":"/api/acts/ad-cessna-170-61-alternate-static-source-valve-inspection/history","analysis":"/api/acts/ad-cessna-170-61-alternate-static-source-valve-inspection/analysis","conflicts":"/api/acts/ad-cessna-170-61-alternate-static-source-valve-inspection/conflicts","importantCases":"/api/acts/ad-cessna-170-61-alternate-static-source-valve-inspection/important-cases","documents":"/api/acts/ad-cessna-170-61-alternate-static-source-valve-inspection/documents"}}