The reporter/s raised a concern regarding the maintenance schedule for the [aircraft type] fleet.
The reporter/s state that maintenance standards of several [aircraft type] has recently declined, citing inadequate spare parts, ground time and engineering staff as factors.
The reporter/s believe that on occasion, maintenance staff broadly apply MEL’s to ensure aircraft remain on schedule, rather than completing repairs/replacing specific items as necessary. Once MEL’s expire, a perfunctory attempt is made to rectify the problem, rather than ensuring a permanent or enduring repair or replacement. As a result, the problem re-occurs (as anticipated), and the same MEL is reapplied. Essentially, the reporter/s believe that [Operator] is prolonging the duration of the MEL rather than addressing it at the first viable opportunity as per [Operator] DDG preamble.
The reporter/s advise that Engineering Orders are treated in much the same way, in which they are applied repeatedly for the same issue, rather than every effort being made to repair/replace the item. Whilst these engineering measures operate within CASR requirements, the EO’s and MEL’s are not being utilised in the manner they were designed for. i.e. a temporary fix to ensure the aircraft can return to the maintenance base to effect repairs, source parts or organise downtime.
The reporter/s provided several instances which the reporter/s believe support the safety concern;
however these cannot be used in this report due to concerns it would identify the reporter/s. One example that can be provided relates to [aircraft registration] twice operating with unserviceable overhead panel lights, resulting in flight crew being unable to see emergency lights, fire switches, anti-ice, pressurisation, starter and ignition, bleed air, and fuel jettison systems when the aircraft operates in night conditions.
In addition, the reporter/s state that the [aircraft type] are not being washed as regularly as they
previously have, resulting in the exterior of some aircraft regularly being sub-standard. As a consequence, possible fluid leaks, corrosion or fractures are not visible to the flight crew conducting pre-flight inspections on the landing gear.
The reporter/s state that absolute minimal resources are currently being dedicated to the [aircraft type] fleet resulting in a safety risk.
Operator's response (Operator 1)
In relation to the specific concerns raised by the reporter we would like to provide the following information:
[Operator] operates under the highest level of regulatory approval and safety available under the Civil Aviation Safety Regulations (CASR 1998) for Regular Public Transport operations, namely CASR Parts 42 and 145.
[Operator] holds both CASR Part 42 Continuing Airworthiness Management Organisation (CAMO); and CASR Part 145 Approved Maintenance Organisation (AMO) approvals. The comprehensive requirements for the management of continuing airworthiness under CASR Part 42 includes specific requirements to ensure aviation safety risks are managed and that the travelling public is afforded the highest available level of safety. CASA, as the independent aviation safety regulator, ensures [Operator] complies with all regulatory approvals.
The CASR Part 42 requirements include: holding a CAMO approval, operating under the CASA approved Safety Management System of the [Operator] Air Operators Certificate, having an approved maintenance program for each aircraft, having an approved reliability program that monitors the effectiveness of the aircraft maintenance program, active management of aircraft defects and deferrals to ensure aircraft are never operated with a defect that may affect the aircraft’s airworthiness, conducting an annual airworthiness review for each aircraft and ensuring that all required maintenance is completed before any aircraft operation.
The [aircraft type] fleet is maintained under an Approved Maintenance Program which is based on manufacturer and regulatory requirements, which all [aircraft type] operators worldwide are required to take into account when developing maintenance programs for their aircraft. The majority of the maintenance tasks in the program and their intervals are developed in accordance with the industry standard (Maintenance Steering Committee (MSG-3)) that is used as the basis for the development of all modern RPT aircraft. In addition to such tasks, the maintenance program contains scheduled maintenance tasks that are required to meet additional regulatory requirements as well as tasks recommended by [manufacturer] based on worldwide fleet experience, and those added by [Operator] from its own operational experience.
Inherent in the philosophy of the maintenance program is the understanding that all items of significance, whether structural or system related, are maintained through inspections, functional checks, operational checks, restorations, and servicing tasks scheduled at an intensity and interval appropriate to the significance of the item, its likely method and rate of degradation, and its failure effect.
Although the [aircraft type] fleet is scheduled to be removed from service, [Operator] continues to maintain the aircraft in accordance with the maintenance program that meets the regulatory and manufacturer requirements mentioned above. The maintenance program has not been varied significantly in recent years in terms of scope or maintenance intervals for these requirements. Additionally in accordance with the program, [Operator] has been performing the deepest level checks (‘D’ Checks) on its aircraft during the last 12 months. This is a significant investment in the aircraft, with over 40 days of heavy maintenance effort for each check. Through the maintenance conducted, [Operator] monitors findings such as corrosion, for each aircraft registration. For example, [aircraft registration] had no significant corrosion findings at its last ‘D’ check performed in 2015 or its most recent C check performed in 2017.
There are several key system health indicators which are reviewed daily and monitored consistently including the aircraft fleets’ dispatch reliability, and application rates for MELs. Both these measures are at normal levels for the [aircraft type] fleet with no adverse trend changes identifiable. In relation to the specific information provided for [aircraft registration] and the application of MEL [number], a review of the maintenance records for this aircraft clearly demonstrate the effectiveness of the pro-active continuing airworthiness management and maintenance arrangements that [Operator] has in place to manage aircraft defects, in accordance with the requirements of the MEL, which in this case provides for 10 days of operation (excluding the day of discovery) to rectify the defect - again emphasising that this does not affect the airworthiness of the aircraft.
The defect in this case was initially reported on 19th Nov and MEL applied. On the 21st Nov the light dimmer was replaced, however, this did not rectify the defect and the MEL continued. On the 24th Nov another dimmer unit was installed which successfully resolved the defect and the MEL was removed. The aircraft operated until 27th Nov when the defect reoccurred necessitating application of the MEL once again. On the 1st Dec additional troubleshooting was undertaken which included replacement of the system fuse with the system found serviceable. Given the history, the MEL was not removed to allow for ongoing monitoring of the system. On the 4th December the defect reoccurred whilst the MEL was still applied, and on 5th Dec all panel lights, and fuses where replaced with no subsequent defects reported. [Operator] continued to take positive maintenance action, and manage an intermittent defect to successful resolution, whilst at all times remaining compliant with the requirements of the MEL and ensuring there were no airworthiness issues with the aircraft concerned.
As with most [type] aircraft in the [Operator] fleet, aircraft exterior wash programs have been performed on condition, with Sydney being one of the few bases where aircraft washes can occur, due to environmental approvals. [The Operator] has recently updated the wash program for its [aircraft type] to schedule set time intervals between aircraft washes. This change has improved the aircraft planner’s visibility of the requirement and allows washes to be more effectively scheduled.
[Operator] would again like to thank the ATSB for the opportunity to provide information in relation to this report and demonstrate the substantial investment that is being made into ensuring the ongoing continuing airworthiness and maintenance of the [aircraft type] fleet (an aircraft type which [the Operator] has operated for over [number] years) to the highest possible standards.
Regulator's response (Regulator 1)
The [Operator] reply is succinct and from the information supplied there are no further comments from CASA. As a follow up, two Airworthiness Inspectors have been scheduled to go onsite to review the [aircraft type] fleet management with the [Operator] Part 42 CAMO.