AD/INST/53 - Shadin ADC-2000 Units

The central concept is an air data computer (ADC), an electronic device that calculates and outputs parameters such as altitude, airspeed, and vertical speed based on pitot-static pressure inputs. The Shadin ADC-2000 is a specific model integrated with an Electronic Flight Information System (EFIS), which replaces traditional analogue instruments with digital displays. The AD targets altimetry accuracy: the requirement that altitude information presented to the pilot is correct within a tolerance of 75 feet when compared across the ADC and EFIS. A discrepancy exceeding 75 feet triggers the placard requirement. The placard limits flight to Visual Meteorological Conditions (VMC) only, meaning flights in Instrument Meteorological Conditions (IMC) or under Instrument Flight Rules (IFR) are prohibited. This is a significant operational restriction because IFR and IMC rely on instrument readings for navigation and separation; an aircraft certified for IFR flight must have trustworthy altitude data. The directive distinguishes between configurations B, C and D of the ADC-2000, implying that earlier or later hardware/software versions may not exhibit the fault. The upgrade specified in Requirement 3 is a modification performed by the manufacturer (Shadin) to correct the underlying issue; it is not a field repair. The AD introduces an interim procedure from Shadin Service Bulletin SB28-05-002 Rev C as the pre-flight check method. That bulletin is incorporated by reference and must be obtained from Shadin to perform the check. Another key concept is the Maintenance Release, a document that records the airworthiness status of an Australian-registered aircraft. Entering the pre-flight check requirement in its Maintenance Required Section makes it a recurring item that must be certified before each flight, similar to a minimum equipment list item. The AD also refers to minimum equipment requirements, meaning the list of instruments and equipment required for the aircraft’s certificate of airworthiness to remain valid for the intended flight. If an aircraft needs the ADC to meet those requirements (e.g., for IFR flight), and the ADC is not upgraded, the placard effectively prevents IFR/IMC operation, but VFR flight may continue if the aircraft otherwise complies with its equipment list. The Return Merchandise Authorization (RMA) number from Shadin is a logistical prerequisite for returning the unit. The directive does not specify the upgrade cost, turnaround time, or consequences of failing to upgrade; those are left to commercial arrangements with Shadin.

The AD directly affects operators of any aeroplane that has a Shadin ADC-2000 air data computer with part numbers 962830A-1-S-8, 962830A-2-S-8 or 962830A-3-S-8 in configurations B, C or D, regardless of the aircraft manufacturer or model. The AD lists specific aircraft types known to have these units installed, but Note 1 states that the list is not exhaustive. Affected manufacturers include Alliance Aircraft Group (H-250), B-N Group (BN2A), Bombardier (DHC-3, DHC-6), Cessna (various 100, 200, 300 series models), de Havilland (DHC-2), and The New Piper Aircraft (PA-28, PA-31, PA-32, PA-34 series). However, any aircraft type with those part numbers and configurations is caught, regardless of whether it appears on the list. The AD applies to aircraft operating under Australian regulatory jurisdiction, i.e., those registered in Australia or operated by an Australian operator under a Australian air operator’s certificate. It also affects maintenance organisations and licensed aircraft maintenance engineers (LAMEs) who perform the required entries on the Maintenance Release and certify compliance. They must ensure that the pre-flight check is entered correctly and that the placard is installed when required. Pilots are affected: the pre-flight check can be conducted by a pilot (other than a student pilot) endorsed on the type. That means the pilot must hold a type rating or equivalent endorsement on the specific make and model, and must not be a student pilot (who lacks the qualifications to perform such airworthiness checks). After placarding, only pilots flying in VMC may operate the aircraft; IFR flights are prohibited. Aircraft owners are affected by the cost and logistics of returning the ADC to Shadin in the United States for upgrade within 15 months. They must also bear the cost of any downtime while the unit is away. Shadin (the manufacturer) is affected indirectly: it must perform the upgrades upon receipt and supply an RMA number. The AD does not compel Shadin to do this, but the AD’s effectiveness depends on Shadin’s capacity. Finally, the AD affects CASA itself, which is responsible for monitoring compliance, handling exemption requests, and possibly issuing subsequent directives if Shadin cannot perform the upgrades in time.

The primary duty under the AD is the obligation of the operator (typically the registered owner or the person who manages the aircraft) to ensure compliance with all four requirements. Duty 1: within 25 hours time-in-service after 23 January 2006, and before each flight thereafter until the ADC is upgraded, perform the pre-flight check described in Shadin SB28-05-002 Rev C, Paragraph E. Duty 2: if the check shows an altimetry discrepancy exceeding 75 feet, install a placard reading “FLIGHT IN IMC OR UNDER IFR NOT PERMITTED” before further flight. Duty 3: return all affected ADCs to Shadin’s repair facility for upgrade within 15 months after the effective date. Duty 4: after the effective date, do not install any non-upgraded ADC-2000 (with those part numbers/configurations) as an initial installation or as a replacement spare. A critical duty is that compliance with Requirement 1 must be entered on the Maintenance Release in the Maintenance Required Section, and the compliance must be certified before each flight. This imposes a recurring documentation obligation that cannot be delegated to a maintenance engineer; the pilot performing the check must sign off. The duty applies even if the ADC has never shown a discrepancy; the check is mandatory at each pre-flight until upgrade. The operator also has the duty to remove the placard after the upgraded ADC is reinstalled. Rights include: the right to have a pilot (other than a student pilot) endorsed on the type perform the check, rather than a licensed aircraft maintenance engineer. That reduces cost and speed of compliance. The operator has the right to obtain an RMA from Shadin before returning the unit. After upgrade and reinstallation, the operator has the right to remove the placard and resume IFR/IMC operations. The operator also retains the right to fly the aircraft under VFR after placarding, provided the aircraft meets minimum equipment requirements without the ADC’s altitude function (if permissible under the aircraft’s type certificate data sheet). Note that the AD does not create a duty to perform the upgrade themselves; they may return the unit to Shadin or contract Shadin to perform it. The AD also implies a right to operate the aircraft with a placarded ADC temporarily; the limitation is only on IMC/IFR flight. The operator has no right to install a non-upgraded ADC after the effective date; that is prohibited outright.

The AD itself does not contain a penalty clause; it is a regulatory instrument made under the Civil Aviation Act 1988. Enforcement would occur under the general provisions of that Act and the Civil Aviation Regulations (CAR) and Civil Aviation Safety Regulations (CASR) concerning airworthiness and operating limitations. Breach of an airworthiness directive is a breach of the condition of the aircraft’s certificate of airworthiness. Operating an aircraft that does not comply with an AD may result in criminal prosecution for a safety breach under the Criminal Code or civil penalty proceedings under the Civil Aviation Act. Specifically, under regulation 42ZA of CAR 1988, it is an offence to operate an aircraft that does not meet the applicable airworthiness standards, which include compliance with ADs. The maximum penalty for an individual may be a fine of up to 5,000 penalty units (currently around $1.1 million) or 2 years imprisonment, and for a body corporate up to 50,000 penalty units (around $11 million). Additionally, CASA can suspend or revoke the aircraft’s certificate of airworthiness until compliance is demonstrated. The Director of Aviation Safety may issue a direction to ground the aircraft or impose operating limitations. The AD’s requirement that the pre-flight check be entered on the Maintenance Release and certified before each flight creates a paper trail; failure to make that entry could itself be an offence of operating without a valid maintenance release. For the placard requirement, flying IFR or IMC with the placard installed would be a direct violation and could be treated as reckless endangerment. The AD does not specify inspectors’ powers, but CASA authorised officers may examine the aircraft and its records, and may issue a notice of non-compliance. The AD cross-references FAA AD 2005-25-08; while that FAA AD is not directly enforceable in Australia, it shows that the US FAA has already taken action, which may prompt CASA to take parallel enforcement. There is no provision in the AD for extension or exemption; operators would need to apply to CASA for an exemption under the Act. The cost of non-compliance includes not only potential fines, but also liability for any incident caused by altitude errors. If an operator fails to comply and an aircraft suffers an accident, the operator could face civil damages claims and potential criminal negligence charges.

This AD is a delegated legislative instrument under the Civil Aviation Act 1988, specifically under the regulation-making powers for airworthiness. It sits within the broader framework of Part 21 of the Civil Aviation Safety Regulations 1998 (CASR), which governs design, production, and continuing airworthiness of aircraft and components. Compliance with this AD is mandatory for the aircraft to maintain its certificate of airworthiness under CASR 21.191 or equivalent. The AD interacts with the Maintenance Release required by CAR 47 and CASR Part 42. The AD overrides any less restrictive maintenance requirements by imposing a specific pre-flight check. It also interacts with the Minimum Equipment List (MEL) for the aircraft. If the aircraft’s MEL requires the ADC for IFR flight, then after placarding the aircraft cannot be operated IFR; the placard effectively creates a new limitation not in the original flight manual. The AD also interacts with the Aircraft Flight Manual (AFM); the placard must be in addition to any AFM limitations, and it may conflict if the AFM permits IFR flight. In practice, the placard becomes an operating limitation that is likely to be incorporated into the AFM or as a temporary amendment. The AD cross-references FAA AD 2005-25-08, meaning that if the aircraft is also registered in the US or operates under a US certificate, it must comply with that AD as well. However, for Australian-registered aircraft, only this CASA AD is directly enforceable. The AD also incorporates by reference Shadin Service Bulletin SB28-05-002 Rev C. Operators must obtain that document; it becomes a mandatory part of the compliance procedure. The AD does not create a statutory right to refund or damages from Shadin if the upgrade fails; that is a contractual matter. The AD interacts with the Convention on International Civil Aviation (Chicago Convention) insofar as CASA’s actions must be consistent with standards and recommended practices. Finally, the AD may affect the operator’s liability insurance: non-compliance could void coverage if an incident occurs while flying with a known non-upgraded ADC. The AD does not specifically address privacy or data issues; those are not relevant.

The text of the AD as provided shows effective date 23 January 2006, issued on 16 December 2005 by Charles Lenarcic, Delegate of CASA. The document itself is AD/INST/53, numbered 2/2006 DM. There is no indication in the source text of any amendments to this AD, either before or after this version. However, as a matter of CASA practice, airworthiness directives can be amended or superseded by later directives. The reference to FAA AD 2005-25-08 Amdt 39-14401 indicates that the FAA AD has an amendment number (Amdt 39-14401), meaning that the FAA has updated its AD at least once. CASA may issue a new AD superseding this one, or may issue an amendment via a new instrument. The source text appears to be the original version. The AD’s expiry or sunset is not stated; ADs remain in effect until explicitly superseded or cancelled. Operators should check CASA’s current airworthiness directive database for any subsequent actions. The AD does not contain a provision for periodic review. Given that the AD requires upgrades within 15 months (by 23 April 2007), it is possible that after that date the non-upgraded units would be removed from service, and the ongoing pre-flight check requirement would cease for upgraded units. However, the AD still prohibits installation of non-upgraded units, so it remains in force as a permanent installation prohibition. Operators who upgraded within the 15 months no longer need to perform the pre-flight check before each flight, but they still must comply with the installation prohibition. The AD has no expiration date on its face; it is likely still in effect today for any units that were never upgraded, though that scenario is improbable. The amendment history of the underlying FAA AD (2005-25-08) may have changed the compliance times or part numbers, but CASA’s AD would need to be separately updated to reflect those changes. As of this writing, no superseding CASA AD is known to me; the source does not mention any.

The source text does not mention any litigation related to AD/INST/53. Airworthiness directives from CASA are infrequently challenged in court because they are technical and safety-based, and operators typically comply to maintain certificates of airworthiness. There is no record in the source of any proceedings in the Administrative Appeals Tribunal or Federal Court concerning this specific AD. However, the underlying issue that prompted the AD (incorrect altitude display) could give rise to product liability claims against Shadin or the aircraft manufacturers, but that is not within the scope of the AD. The AD itself is an administrative instrument that can be reviewed under the Administrative Decisions (Judicial Review) Act 1977 if a person is aggrieved, but such challenges are rare due to the limited grounds (e.g., failure to take into account relevant considerations). The FAA AD 2005-25-08 has likely been subject to review by the US FAA and possibly compliance actions, but that is separate. In Australia, CASA enforcement actions (e.g., suspension of a certificate of airworthiness for non-compliance) could be appealed to the AAT. No such case is reported in this source. The lack of litigation history suggests that the directive was implemented without controversy; the compliance burden was modest (pre-flight check and eventual upgrade), and the safety rationale was widely accepted. However, an operator who believed the AD was unnecessary or that the measured tolerance (75 feet) was too stringent might have sought reasons from CASA, but no evidence of that exists in the source. The AD’s reference to “Unsafe operating condition” in the background is a standard formulation and has not been successfully challenged. Overall, the litigation history is essentially nil for this instrument, which is typical for a narrow component-related AD.

Several traps arise from the wording of the AD. First, the pre-flight check requirement must be entered on the Maintenance Release in the Maintenance Required Section before each flight, not just the first flight. This creates a recurring airworthiness task similar to a Life Limited Part or a scheduled inspection. Failure to enter the task on the Maintenance Release before the first flight after the effective date (within 25 hours TIS) means the aircraft technically does not have a valid maintenance release for that flight. Second, the check must be performed by a pilot endorsed on the type, but not a student pilot. If the only pilot available is a student or not endorsed, the check cannot be performed, and the aircraft cannot fly. Operators should ensure that at least one suitably endorsed, non-student pilot is on hand before each flight. Third, the placard must have letters at least 6mm high. A hand-written sign with smaller letters or a sticker that is not legible is non-compliant. Fourth, the placard text is specified exactly: “FLIGHT IN IMC OR UNDER IFR NOT PERMITTED” in bold. Variations like “No IFR” or “VFR Only” are not compliant. Fifth, the AD does not specify where on the instrument panel the placard must be placed, only “in clear view of the pilot”. A good practice is to place it near the altimeter or EFIS. Sixth, the pre-flight check procedure is contained in a service bulletin that is not reproduced in the AD. Operators must obtain Shadin SB28-05-002 Rev C. That document may be proprietary or require payment. Consulting the wrong revision (e.g., Rev A or B) could lead to incorrect checking. Seventh, the 75 feet tolerance applies to the difference between the ADC reading and the EFIS reading; it is not a comparison to a known ground altitude. If the aircraft does not have an EFIS? The AD references EFIS altimetry; some aircraft may have the ADC feeding other instruments. The AD says “EFIS altimetry accuracy”; but if the aircraft has no EFIS, is the ADC still affected? The applicability states the ADC-2000 units “are known to be installed in” aircraft; the note implies EFIS is likely present. If the aircraft has non-EFIS displays, the AD still applies because it covers the ADC itself. But the check procedure in the service bulletin may assume EFIS. Operators must clarify with Shadin or CASA. Eighth, the RMA number must be obtained before returning the ADC. Return without RMA may be rejected. Ninth, the 15-month compliance for upgrade runs from the effective date, not from the date of installation of the ADC. An ADC installed after the effective date must already be upgraded (Requirement 4). Tenth, the AD prohibits installation of non-upgraded units as spare parts. If a repair centre installs a used ADC as a replacement without checking its upgrade status, that would violate Requirement 4. Eleventh, the note about minimum equipment requirements: after placarding, the aircraft may only be flown if minimum equipment are still met. This means the aircraft must be able to operate VFR without the ADC altitude function (assuming the aircraft’s MEL or type certificate allows it). If the aircraft requires the ADC for VFR flight (unlikely), then even VFR flight is prohibited. Twelfth, the AD does not address what happens if the upgrade is not available within 15 months due to supply chain issues. The operator would have to seek an extension from CASA; flying after the 15-month deadline with an un-upgraded ADC would be non-compliant even if the unit passes the pre-flight check.

Compliance with AD/INST/53 involves a step-by-step process tied to the four requirements and their deadlines. Step 1: Immediately upon the effective date (23 January 2006) ensure that no non-upgraded ADC-2000 (P/N as listed, configurations B, C, D) is installed on any aeroplane under your control, whether as initial fitment or as a replacement spare. Any existing stock of such units must not be installed unless upgraded. Step 2: Within 25 hours time-in-service after that date, perform the pre-flight check described in Shadin Service Bulletin SB28-05-002 Rev C, Paragraph E. Obtain a copy of that bulletin from Shadin technical support. The check may be performed by a pilot who holds an endorsement on the aircraft type and is not a student pilot. The pilot must compare the ADCs altitude output with the EFIS display; if the difference is 75 feet or less, the ADC passes. Step 3: Before the next flight after the 25-hour check, and before each subsequent flight until the unit is upgraded, perform the same check again. Enter the requirement on the Maintenance Release in the Maintenance Required Section. This is typically done by a licensed aircraft maintenance engineer or the pilot if authorised under the operator’s maintenance procedures. The entry must be certified before each flight, usually by the pilot signing or ticking a box. Step 4: If the check reveals a discrepancy greater than 75 feet, do not fly the aircraft until a placard is installed. The placard must have bold letters at least 6mm high reading “FLIGHT IN IMC OR UNDER IFR NOT PERMITTED”. Install it in clear view of the pilot, e.g., on the instrument panel near the altimeter. After placarding, flight is permitted only in VMC (Visual Meteorological Conditions) and only if the aircraft can meet its minimum equipment requirement without the ADC’s altitude data. Step 5: Arrange to return the affected ADC to Shadin Repair Facility for upgrade. Contact Shadin Technical Support to obtain an RMA number before sending the unit. Coordinate with a maintenance organisation to remove the ADC and install a temporary replacement if available, or accept the aircraft will be down while the unit is shipped. Step 6: Within 15 months of the effective date (i.e., by 23 April 2007), have the upgraded ADC reinstalled. Once reinstalled, the pre-flight check requirement ceases (since the upgrade is complete). Remove the placard. Step 7: Record all actions in the aircraft’s maintenance records, including the removal, return, upgrade, reinstallation, and removal of the placard. Ensure that the Maintenance Release entry for the pre-flight check is removed or annotated as no longer required after upgrade. Step 8: For any future installations of ADC-2000 units with those part numbers and configurations, verify that they have been upgraded per Requirement 3. Obtain documentation from Shadin confirming upgrade status. Do not install any unit that lacks that documentation. This compliance path requires coordination with pilots, engineers, and Shadin. The primary challenge is obtaining the service bulletin and managing the 25-hour recurring check, which could be as frequent as multiple times per day for high-utilisation aircraft. Operators should consider scheduling the upgrade as early as possible to eliminate the recurring requirement and restore full IFR capability.