AD/CESSNA 170/78 Amdt 1 - Flexible Fuel Hose End Fittings

Airworthiness Directive (AD). This is a legally enforceable rule made by CASA under the Civil Aviation Act 1988 and the Civil Aviation Safety Regulations 1998. An AD mandates inspection, modification or operational restriction on an aircraft type when an unsafe condition is found to exist in that type and is likely to exist in other aircraft of the same type. Compliance is mandatory; the aircraft may not be operated unless the AD is complied with, and the operator must record compliance in the maintenance records.

Flexible fuel hose end fittings. These are the metallic connector ends crimped or swaged onto the flexible rubber or PTFE hose runs in the engine fuel system. The AD is concerned with the threaded joint where the hose end fitting connects to a rigid component such as the fuel pump, fuel injector servo, or fuel manifold valve. The identified failure mode is that these fittings may be under-torqued, which can cause fuel leaks or disconnection during flight.

Torque value and torque putty/paint. Torque is the rotational force applied to tighten the fitting to a specified value, measured in inch-pounds or foot-pounds. The AD requires use of the torque values specified in Cessna Service Bulletin SB07-71-01, Revision 1. After torquing, torque putty or paint must be applied to the joint to provide a visual indication that the fitting has been torqued and to detect subsequent loosening. The appendix explicitly requires removal of old torque putty or paint before torquing and application of fresh putty after.

Time-in-service (TIS). This is a measure of operating time on the aircraft or engine. The initial compliance is within the next five hours TIS after the effective date. If the aircraft is already overdue for inspection because it has been in service without the AD being applied, then the operator must comply before further flight. The concept of 'before further flight' is an immediate grounding requirement; the aircraft cannot legally depart until the inspection and any necessary corrective action is completed.

Garmin G1000 equipped versus non-equipped. The AD splits the affected aircraft into two groups. Group 1 aircraft are those not equipped with the Garmin G1000 integrated avionics system. Group 2 aircraft are equipped with G1000. The difference in hose routing reflects different fuel system configurations between analogue and glass-cockpit variants. Group 2 aircraft have a different hose from fuel injector servo to fuel flow transducer and then to fuel manifold valve, whereas Group 1 non-turbo models have the servo directly to the manifold valve. Turbo models (applicable only to non-G1000 172R/S? The AD does not specify turbo variants of 172R/172S, but the text says 'turbo models only' for certain hose runs, indicating that some serial numbers may have a turbocharged engine variant). The distinction is important for determining which hoses must be inspected.

FAA AD cross-reference. The AD notes that it relates to FAA AD 2007-08-03 Amendment 39-15020, which supersedes FAA AD 2006-17-04. CASA has adopted the FAA AD as the basis for Australian action, but with local amendments including the addition of specific serial numbers and the appendix. This is a common mechanism: CASA issues its own AD that imports the technical content of the FAA directive while ensuring it applies to Australian-registered aircraft.

Appendix. The appendix is part of the AD and contains specific inspection instructions. It sets out six steps: remove cowlings; remove old torque putty; loosen the hose end fitting while restraining the other end; torque to proper value using the service bulletin; apply torque paint; and if any non-hose fitting rotates, stop, disconnect, inspect and rectify. This appendix supplements the service bulletin and provides the legally binding procedure that must be followed.

The AD applies directly to the owners and operators of Cessna 172R and 172S aircraft falling within the specified serial number ranges. For the 172R, these are serial numbers 17281244 through 17281364, plus individual numbers 17281366 through 17281372, 17281374 through 17281376, and 17281379. For the 172S, the range is 172S9809 through 172S10349, with a long list of excluded individual serial numbers (e.g., 172S10350 is excluded, 172S10375 excluded, etc.). Only those serial numbers explicitly listed are subject to the AD; all other 172R and 172S aircraft (and all earlier 172 models, and the 170, 175, F172, FR172 series mentioned in the title) are not included, despite the title suggesting a broader scope. The title of the AD says 'Cessna 170, 172, F172, FR172 and 175 Series Aeroplanes' but the applicability block confines the requirement to Models 172R and 172S with the listed serials. This is a typical drafting anomaly where the AD number (AD/CESSNA 170/78) suggests a broader original scope, but subsequent amendments have narrowed or changed applicability. The user of this AD must read the applicability block carefully, not the header. Affected parties include: individual aircraft owners (private and flying schools); commercial operators using these models; maintenance organisations that perform inspections and repairs; licensed aircraft maintenance engineers (LAMEs) who must execute the torque procedure and sign off compliance; and parts suppliers who may need to provide replacement fittings or seals. Indirectly, the AD affects insurers who may require proof of compliance as a condition of coverage, and aircraft buyers who need to verify the AD status as part of a pre-purchase inspection. Also affected is Cessna Aircraft Company, which must maintain and publish Service Bulletin SB07-71-01 and any later approved revisions, and make them available to operators. The AD also affects CASA itself, which must administer compliance monitoring and enforcement. The compliance burden is concentrated on a relatively small number of aircraft. The serial ranges and exclusions mean likely fewer than 200 Australian-registered aircraft are affected (based on typical fleet numbers). However, the cost per aircraft is high relative to the value of a 172. A typical Cessna 172R or 172S might be worth $150,000 to $300,000 AUD; a full compliance inspection taking 2-4 labour hours at $100+/hour plus parts for any defective fittings could cost $500 to $1500. If a non-hose end fitting rotates, the cost escalates because it may require removal and replacement of the rigid component (e.g., fuel pump), adding further parts and labour. The AD does not provide any compensation for this mandatory work; the owner bears the full cost. In economic terms, this is a regulatory tax on owners of those specific aircraft, imposed to solve a safety problem identified in four reports of loose fuel lines. The benefits are reduced risk of engine failure and fuel fires. The cost-benefit trade-off is not assessed in the AD itself; operators simply must comply or ground the aircraft.

Duty to inspect. The primary duty on the aircraft operator is to perform the inspection of the hose end fittings on the listed fuel lines within the first five hours of time-in-service after 25 April 2007. This duty is absolute: the AD does not allow any alternative compliance interval or extension. The inspection must be done in accordance with the instructions in Cessna Service Bulletin SB07-71-01, Revision 1, and the appendix to this AD. The operator may not delegate the duty, but may contract a maintenance organisation to perform the work. However, the operator remains legally responsible for ensuring compliance.

Duty to correct. If any incorrect torque values are found during inspection, the operator must establish correct torque values. This corrective action must be done before further flight. That is a mandatory grounding: the aircraft may not be operated until the torque is set correctly and torque putty applied. The AD does not specify time-in-service for corrective action; it is immediate.

Duty to restrain fittings. The appendix imposes a duty on the person performing the torque procedure to use a suitable tool to restrain the other end fitting of the joint to preclude rotation. If the non-hose end fitting rotates, the operator must stop the procedure, totally disconnect the joint, remove the rotated fitting, clean and visually examine it, replace seals or sealant, reinstall, torque, and reconnect. This duty is a procedural safeguard to avoid damaging rigid fittings.

Right to use later approved revisions. The AD permits the use of later FAA-approved revisions of Cessna Service Bulletin SB07-71-01. If Cessna issues Revision 2 or higher and the FAA approves it, the operator may use that instead of Revision 1. This provides flexibility if the manufacturer updates torque values or procedures. However, the operator must verify FAA approval; merely a later revision number is not sufficient unless it is specifically approved by the FAA.

Right to alternative means of compliance. The AD does not explicitly mention alternative means of compliance (AMOC). However, standard CASA practice under CASR Part 11 allows request for AMOC approval from CASA. An operator who believes that a different method provides equivalent safety (e.g., replacing all hoses instead of just torquing) could apply for an AMOC. The AD's silence on AMOC does not preclude it; the general regulatory framework provides that avenue. But any AMOC must be in writing and approved by CASA before it may be used.

Right to operate if complied. Once the initial inspection and any corrective action are completed and recorded, the aircraft may continue to operate. The AD does not require repetitive inspections, so the duty is satisfied unless a hose is replaced or disturbed. If a hose end fitting is loosened for any reason, the torque procedure must be repeated as part of the maintenance task.

Record-keeping duty. The compliance history of the AD must be recorded in the aircraft maintenance records. This is not explicit in the AD but flows from the continuing airworthiness obligations under CASR Part 42. Typically, a maintenance release or logbook entry certifies compliance with the AD and lists the torque values found and any corrective action. Failure to record may lead to enforcement for non-compliance even if the work was actually done.

The AD itself does not set out penalty amounts; penalties arise under the broader aviation legislation. Under the Civil Aviation Act 1988, a person who contravenes an airworthiness directive is guilty of an offence. Section 20A of that Act creates an offence for operating an aircraft that is not airworthy, and section 28 provides for CASA to issue directions. The Civil Aviation Safety Regulations 1998 (CASR) Part 42, Division 42.10 prescribes continuing airworthiness requirements. Specifically, regulation 42.610 requires an operator to ensure that all applicable airworthiness directives are complied with. Contravention can attract a maximum penalty of 50 penalty units for an individual and 250 penalty units for a body corporate (at 2007 rates, approximately $5,500 and $27,500 respectively, but subject to indexation). More significantly, CASA can suspend or cancel the aircraft's certificate of airworthiness if an AD is not complied with, grounding the aircraft indefinitely until compliance is demonstrated. CASA also has powers to issue enforceable undertakings or take civil proceedings for an injunction. The enforcement regime is risk-based: CASA conducts surveillance audits and may issue a direction to ground the aircraft immediately. If an owner operates an aircraft knowing an AD is overdue, that is considered a serious breach and CASA may refer it for prosecution or take administrative action. The AD's compliance timeline (5 hours TIS) is tight; an operator who misreads the effective date or inadvertently flies a few hours over could face enforcement even if no incident occurs. The AD includes a note that FAA AD 2007-08-03 refers; the text of the Australian AD is likely to be inspected alongside the FAA version. CASA may cross-check FAA compliance data for imported aircraft. Additionally, maintenance organisations that falsify compliance records or sign off incomplete work face separate penalties under CASR Part 145 (maintenance organisations) and Part 66 (licensing of maintenance engineers). The practical enforcement risk is moderate: the affected aircraft fleet is small, and CASA may focus on known operators. However, the high consequence of engine failure means CASA will treat non-compliance seriously. The AD does not provide for any grace period beyond the initial 5 hours; an overdue aircraft is technically unairworthy from the first hour past the limit.

This AD operates within a hierarchy of aviation safety regulations. It is a continuing airworthiness requirement under CASR Part 42. Specifically, regulation 42.610 requires the registered operator to ensure compliance with all ADs applicable to the aircraft. The AD itself is a legislative instrument made under section 28 of the Civil Aviation Act 1988 and section 12 of the Civil Aviation Regulations 1988 (as the CASR transition allowed). It has the force of law. Compliance with the AD is a condition for the validity of the aircraft's certificate of airworthiness under CASR Part 21. If the AD is not complied with, the certificate of airworthiness is considered invalid and the aircraft cannot legally fly. The AD also interacts with the Civil Aviation (Offences) Regulations 1998, which create strict liability offences for operating aircraft not in accordance with its airworthiness certificate. The AD incorporates by reference an FAA airworthiness directive and a Cessna service bulletin. The FAA AD itself is not directly enforceable in Australia, but the Australian AD makes compliance with the FAA AD's substantive requirements (as modified by the appendix) mandatory. This creates a cross-jurisdictional compliance chain: the operator must obtain the Cessna service bulletin, which is a proprietary document subject to copyright. Operators must purchase or obtain it from Cessna (now Textron Aviation). The AD does not reproduce the torque values, so the operator cannot comply without the bulletin. This imposes an additional cost and potential delay. The interaction with the Australian Consumer Law (ACL) is minimal; any dispute about the quality of the service bulletin or the AD's reasonableness is not actionable under the ACL because the AD is a regulatory instrument. However, if a maintenance organisation performs the work negligently and causes damage, the ACL and common law tort principles apply. The AD also interacts with the aircraft's type certificate data sheet. The torque values specified in the service bulletin likely derive from the original type design or from later approved data. If the torque values conflict with the maintenance manual (unlikely, as the SB supersedes), the AD requires following the SB. For import and export, aircraft being imported into Australia from the United States must have a CASA AD compliance statement. The FAA AD may have been complied with in the US, but the Australian AD may have additional serial numbers or appendix requirements. The importer must ensure that the aircraft's compliance meets the Australian AD, not just the FAA AD.

The original AD/CESSNA 170/78 was issued by CASA with an effective date of 4 September 2006. That original directive addressed the same issue of flexible fuel hose end fittings on Cessna 172R and 172S aircraft but with a different, narrower serial number applicability and without the appendix containing specific inspection instructions. The original AD presumably adopted FAA AD 2006-17-04 (Amendment 39-14725), which was superseded by the later FAA AD 2007-08-03. Amendment 1, which is the subject of this deep dive, became effective on 25 April 2007. The amendment expanded the applicability by adding additional serial numbers for both the 172R and 172S models, incorporating the newer FAA AD reference (2007-08-03), and adding the appendix with the step-by-step torque procedure. The amendment also changed the compliance timing: the original AD had a compliance time of 10 hours or something? Not stated, but the amendment specifies 'within the next 5 hours time-in-service' for initial inspection and 'before further flight' for correction. The amendment also added the note referencing FAA AD 2007-08-03 and that it supersedes the earlier FAA AD. This amendment history is important for operators who may have complied with the original AD but whose aircraft serial numbers were added only in the amendment; they must now perform the inspection even if they previously complied under the original scope. Also, the appendix is new and may impose additional procedural requirements (e.g., removing old torque putty, restraining both ends) that were not in the original AD or in the FAA AD alone. Operators who completed the inspection using only the service bulletin prior to the amendment might need to redo the work to meet the appendix steps. The AD document itself is a single page plus the appendix and signature page. It is not complex, but the amendment history means that records may need to distinguish between compliance with the original AD and with Amendment 1. CASA's online database may show the current version only; operators must check the effective date of their compliance.

There is no recorded Australian litigation directly challenging CASA AD/CESSNA 170/78 Amdt 1. This is unsurprising. Airworthiness directives are rarely litigated because the regulatory scheme gives CASA broad discretion to impose mandatory directives in the interests of safety. Operators generally comply rather than challenge, and the costs of judicial review are high relative to the compliance cost. However, the broader context of administrative law is relevant. If an operator were to challenge the AD, the likely ground would be Wednesbury unreasonableness or that CASA took into account irrelevant considerations. The background section cites four reports of loose fuel lines, two resulting in engine failure. A court would probably find that four reports, even if only a small sample, provide a rational basis for the AD. The fact that the AD is modelled on an FAA directive also bolsters CASA's defence. Another possible challenge could be that the AD improperly delegates to Cessna the determination of torque values without adequate guidance. However, the AD incorporates the service bulletin by reference, a standard and accepted technique. No case has succeeded on that basis in Australia. The AD is also a legislative instrument and subject to disallowance by Parliament, but no disallowance motion was moved. In summary, litigation is hypothetical; the AD has been in force for over 17 years, and no reported challenge exists. The practical risk for operators is not litigation but enforcement action by CASA.

Serial number trap. The title of the AD says it covers Cessna 170, 172, F172, FR172 and 175 series. The applicability block, however, limits it to Models 172R and 172S with specific serial numbers. Many owners of older 172 models (e.g., 172M, 172N, 172P) or the Cessna 170, 175, etc. might mistakenly think they are affected. They are not. Conversely, an owner of a 172R with serial number 17281365 is excluded because that single number is not in the range. The list of exclusions for the 172S is extensive; many serial numbers are omitted. Operators must check their exact serial number against the list, not just the model designation.

Compliance time starts from AD effective date, not from aircraft's last overhaul. The inspection must be done within the next 5 hours TIS after 25 April 2007. For an aircraft that had 100 hours flown since that date, the AD is immediately overdue. The operator must ground it and comply before further flight. The AD does not allow a grace period for aircraft that are already past 5 hours since the effective date.

Before further flight for correction is strict. If the inspection finds any incorrect torque, the aircraft cannot fly until it is corrected. This could cause a delay at an away airport where the operator lacks tools or parts. The AD does not provide any ferry flight permit for repositioning. Plans for such a contingency are essential.

The appendix adds requirements not in the FAA AD or the Cessna service bulletin. The appendix requires removal of all old torque putty, loosening the fitting before torquing to the proper value (not just checking torque), and if any non-hose end fitting rotates, complete disconnection and inspection. A mechanic who only follows the service bulletin may miss these steps and end up non-compliant. The AD says the inspection must use the instructions of the service bulletin 'and the procedures given in the appendix'. Both must be followed.

Torque putty and paint are consumables that must be procured. The AD does not specify which type of putty or paint; it must be suitable for the environment (fuel, heat). The cost is minor, but forgetting to apply it after torquing means the AD step is incomplete and the inspection must be redone.

The AD does not explicitly state the torque values. They are in the Cessna service bulletin, which must be purchased. An operator cannot comply without it. The bulletin is not freely available. This creates a barrier for small owner-operators. There is no grace period for obtaining the bulletin; the compliance clock ticks regardless.

Records must reflect both the AD number and the amendment. The AD number is AD/CESSNA 170/78 Amdt 1. Many logbook entries might only say 'AD/CESSNA 170/78' which is insufficient after the amendment. The entry should state the amendment is complied with, and if the original AD was complied with earlier, the amendment compliance must be recorded separately.

The AD applies only to hose end fittings. It does not address the hose body itself, the clamps, or the rigid fittings. If a hose is old and cracking, it is not required to be replaced by this AD. An operator might fix the torque but still have an unsafe hose. That is a separate maintenance issue.

The appendix step 6 contains a loop. If during any torque procedure the non-hose end rotates, you stop, disconnect, remove, clean, inspect, replace, reinstall, torque, then repeat the torque procedure for the hose end fitting (step 4) and then go to step 6 again if it rotates again. This could lead to an iterative process if the rigid fitting continues to rotate. The operator may need to replace the rigid component (e.g., fuel pump) to achieve a fixed joint. The AD does not cap the cost or require replacement; it just says to repeat the process.

The AD does not address later model 172R/172S beyond the listed serial numbers. Aircraft manufactured after the AD date (e.g., 2008 models) are not covered, but they may have the same design. The operator is responsible for monitoring for later ADs that may include them.

To comply with AD/CESSNA 170/78 Amdt 1, the operator (or the contracted maintenance organisation) must take the following steps:

1. Confirm applicability: check that the aircraft is a Cessna 172R or 172S and that its serial number falls within the listed ranges, taking care to note the exclusions (e.g., 172S10350 is excluded). This requires consulting the exact text of the AD, not a summary.

2. Obtain Cessna Service Bulletin SB07-71-01, Revision 1, or a later FAA-approved revision, from the manufacturer. This bulletin contains the torque values for each hose end fitting. Also note that the AD incorporates the bulletin by reference; only the FAA-approved version is acceptable. Contact Textron Aviation (Cessna) to purchase or download the bulletin.

3. Obtain the required tools and materials: suitable torque wrenches (calibrated), wrenches to restrain the other end fitting, new torque putty or paint appropriate for the operating environment, and cleaning materials (solvent, rags). Ensure the torque wrench is within its calibration period.

4. Schedule the aircraft for the inspection within the next 5 hours of time-in-service. If the aircraft has already exceeded that limit, it must be grounded immediately and the inspection performed before any further flight.

5. Perform the inspection following the appendix steps:

   • Remove the upper and side cowlings.
   • Remove all signs of old torque putty or paint from the fittings.
   • For each hose run listed (depending on group: G1000 or non-G1000), use a suitable tool to slightly loosen the hose end fitting while using another tool to restrain the mating fitting so it does not rotate. The appendix does not specify a loosening amount; just loosen enough to break the bond.
   • Then torque the hose end fitting to the value specified in the service bulletin, again restraining the other end.
   • Apply torque putty or paint to the completed joint.
   • If during the procedure any non-hose end fitting rotates, stop immediately. Disconnect the hose end joint completely. Remove the rotated fitting. Clean and visually examine it. Replace any seals or sealant as needed. Reinstall the fitting and torque it to the applicable requirement. Then reconnect the hose end and repeat the torque procedure for that joint, and check again that the non-hose end does not rotate. This may require replacing the rigid component if it cannot be properly secured.

6. Record the compliance in the aircraft maintenance records. The entry should state: 'Complied with AD/CESSNA 170/78 Amdt 1. Inspection performed per Cessna SB07-71-01 Rev 1 (or later FAA approved revision) and the appendix to the AD. All torque values found within limits or corrected. Torque putty applied.' The date, time-in-service at compliance, and the licence number of the certifying engineer must be included.

7. For future operations, if any of the affected hoses are replaced or disconnected for any reason, the torque and putty procedure must be repeated on those joints. The AD does not require re-inspection of all joints if only one is disturbed, but the disturbed joints must be done.

8. Retain the service bulletin and a copy of the AD for the life of the aircraft. CASA may request evidence of compliance during an audit.

The cost of compliance is not reimbursable. The operator should budget for a few hours of labour, the purchase of the service bulletin, and consumables. If any rigid fitting rotates, additional parts and labour for replacement of the fuel pump, servo, or transducer may be required, costing several hundred to over a thousand dollars. The AD does not prescribe a maximum cost; the operator must restore the aircraft to a condition where the hose end fittings are properly torqued.