Aviation safety issues and actions

Civil Aviation Safety Authority Australian Parts Manufacturer Approval implementation approvals

Issue number: AO-2013-226-SI-07
Who it affects: Operators of aircraft fitted with parts manufactured under those Australian Parts Manufacturer Approvals
Issue owner: Civil Aviation Safety Authority
Transport function: Aviation: Airspace management
Background: Investigation Report AO-2013-226
Issue release date: 21 January 2016
Current issue status: Closed – Partially addressed
Issue status justification:

The ATSB is not satisfied that CASA’s actions in response to safety recommendation AO 2013-226-SI-044 have completely addressed the safety issue.

Safety issue description

Over 1,000 parts were approved by the Civil Aviation Safety Authority for Australian Parts Manufacturer Approval using a policy that accepted existing design approvals without the authority confirming that important service factors, such as service history and life‑limits, were appropriately considered.

Proactive action

Action organisation: Civil Aviation Safety Authority
Date: 21 January 2016
Action status: Released

The ATSB provided the Civil Aviation Safety Authority (CASA) with written information about this safety issue and then followed up with a meeting on 11 February 2015 to discuss the issue. In correspondence following that meeting, CASA advised of the following safety action:

CASA has reviewed its processes and procedures applicable at the time for the appointment of CAR 35 authorised persons and concluded that although CAR 35 regulation referred to design standards and not airworthiness requirements, one of the usual limitations on all CAR 35 instruments was to consider relevant/applicable ADs and therefore the issue of AD consideration was covered in this way. Nevertheless, it appears, on the basis of the ATSB investigation, that, at least in one case, a CAR 35 design approval was given without considering applicable ADs.

In order to assess the potential scope and establish direction of any future actions, if any, CASA has made a decision to conduct a review of the approach of all former CAR 35 authorised persons, before 2003, with regards to the assessment of ADs in their approvals made under CAR 35 regulation. The data for this review will be collected during the scheduled surveillance events, for currently active design authorised persons, and via communication in writing with inactive and retired (former) CAR 35 authorised persons that were active before 2003. Once the results are received, an assessment will be conducted and further action decided. If in the course of collecting data, any adverse trends are noticed, an appropriate interim action will be initiated.

Subsequently, following their review of the draft report, CASA advised that they would not be carrying out any further safety action in respect of this safety issue. 

ATSB comment:

The ATSB acknowledges CASA’s initial action to address this safety issue. However, the ATSB is concerned that this action does not specifically examine the over 1,000 Australian Parts Manufacturer Approvals undertaken by the Regulatory Reform Program Implementation (RRPI) team in 2003. The effect of the policy direction given to the RRPI team, and lack of CASA files containing records of CASA’s engineering assessments of those parts, means there is no assurance that the tie rod manufacturer’s other RPPI-approved APMA parts were not similarly affected by the issues identified with the tie rod replacement parts approval. In support of this, the ATSB has become aware that at least one other part listed on the tie rod manufacturer’s APMA approved by the RRPI, for the DHC-1 Chipmunk aircraft, is the subject of an airworthiness directive that places a life limitation on the part. Like the APMA for the tie rods, there is no mention of the airworthiness directive, or life limitation, on the associated APMA documents.

As a result, the ATSB has issued the following safety recommendation.

Recommendation

Action number: AO-2013-226-SR-044
Action organisation: Civil Aviation Safety Authority
Date: 21 January 2016
Action status: Released

The ATSB recommends that the Civil Aviation Safety Authority takes action to provide assurance that all of the replacement parts that were approved for Australian Parts Manufacturer Approval by the Regulatory Reform Program Implementation team in 2003 have appropriately considered important service factors, such as service history and life‑limits. 

Additional correspondence

Response date: 19 April 2016
Response from: Civil Aviation Safety Authority
Action status: Closed
Response text:

CASA response to the ATSB recommendation appears to go no further than the safety action that was proposed in the previous response to the safety issue. The following safety action proposed will not give CASA the ability to assess the parts approved through its own approval process.

Response date: 18 February 2020
Response from: Civil Aviation Safety Authority
Action status: Closed
Response text:

On 19 April 2016, the ATSB advised that CASA's response did not adequately address the safety issue. CASA has subsequently reviewed its original response to ATSB safety recommendation AO-2013-226-SR-044 and developed an alternative approach to achieving an acceptable level of safety assurance. Consequently, CASA will not be issuing a directive to all CAR 35 design holders to provide CASA with information in relation to APMA approvals as previously advised.


CASA undertook the following activities to make a determination if a reasonable level of safety assurance was already apparent:

  • An evidence-based review of the CASA Service Difficulty Report (SDR) database was conducted to examine the number of APMA part failures. Systemic issues affecting APMA approvals would be consistent with a disproportionately higher rate of premature failure of APMA parts, whether they comprise critical airworthiness parts or not, in comparison with the Original Equipment Manufacturer (OEM) parts they replaced; and
  • An engineering study of the specific manufacturer of the failed tie-rod parts, J&R Aerospace, was conducted. J&R Aerospace manufactured a significant proportion of all APMA parts in Australia. The study [emphasis added]:

a) Reviewed the APMA list of J&R Aerospace parts for any that may be considered critical components likely to be life limited or subject to airworthiness limitations.
b) Performed an analysis of a selected sample of those parts to identify the presence of any design or service life deficiencies. That included determining if the OEM part, upon which the APMA part was designed to replace, also suffered any similar design or service life deficiencies.
c) Sought to establish if there was any evidence of unsafe conditions present in any of the target group of parts.

The analysis of the available SDR data indicated that the J&R parts failure rate was 0.3%. The combined failure rate for all other APMA manufacturers was 1.07%. J&R accounted for 56% of all APMA part types manufactured. The sixteen other APMA manufacturers comprised 44% of the total APMA part types manufactured.

Further analysis was conducted to determine if the failure rate of all APMA parts was, on average, over represented compared to OEM parts. The analysis determined that the failure rate of APMA parts was not over represented compared to OEM parts. In addition, no individual APMA manufacturer exhibited an unusually high failure rate for any of its manufactured parts compared to the equivalent OEM part.

The data indicated that there were no apparent safety issues with any of the APMA parts reviewed. It is CASA's considered view that this provides a reasonable level of safety assurance that parts manufactured under an APMA have appropriately considered service factors, such as service history, life-limits, and airworthiness directives. CASA proposes that the above alternative approach has addressed the safety concern highlighted by the ATSB.

ATSB comment:

The ATSB thanks CASA for the safety action taken to date in an effort to reduce the risk of safety issues as they relate to the identified safety issue and recommendation. However, the ATSB remains concerned about the CASA methodology to identify all underlying issues, specifically given the fact that the assessment is of a ‘sample’ of parts that are critical to flight.

The afore mentioned J & R designed and manufactured Cessna wing attachment fitting with a 100mm stress corrosion crack is another example of a CASA approved J & R Aerospace APMA part that is critical to flight. The ATSB report with regard to the wing attachment fitting was supplied to CASA in 2016, it showed that the fitting had design and manufacture differences when compared to the original part. Those differences included features that made the part more susceptible to stress corrosion cracking.

As highlighted in investigation report AO-2013-226 and safety recommendation AO-2013-226-SI-044, the policy used by the RRPI team in 2003 in the case of APMA applications was deficient and differed from CASA’s documented procedure. In particular, the policy applied in 2003 by the RRPI team did not require confirmation that important service factors, such as service history and life-limits were appropriately considered.

It is not known how many of the 1,000 APMA parts that were approved by the RRPI in 2003 are critical to flight. However, it is the ATSB’s opinion that without assessing all parts that are critical to flight there will be an unacceptable residual risk of part failure leading to an aircraft accident.

On that basis, it would appear at this stage that there is minimal scope for the CASA action in response to safety recommendation AO 2013-226-SI-044 to adequately address the safety issue.

Last update 15 July 2020