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Preparing Stored Aircraft For Return To Service (RTS)

The grounding of hundreds of aircraft in the last 7 or 8 months has led to a wave of issues concerning extended periods of parking and storage.

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Most storage programmes are designed to cater for relatively short episodes and aircraft parked for extended periods of time would often have been in need of major maintenance to rectify concerns about corrosion, leaks, unreliable parts or systems.


As aircraft return to service in large numbers, much more information has become available about issues related to extended downtime. Most of the aircraft parked due to the pandemic have not undergone major maintenance programs. The opposite has, in fact, been true: airlines have generally brought back into service aircraft that did not need a major check since they want to preserve cash.


Meanwhile, Boeing's beleaguered MAX has endured far longer grounding periods and the issues associated with that aircraft will have some relevance for other types grounded for less time.


A key issue to consider is that there are many variables affecting each aircraft in different ways; there is not a 'one size fits all' return to service program. The variations in how aircraft have been parked or stored differ from one extreme to another.


Extreme 1: The aircraft has been stored in an environmentally and temperature-controlled hangar


Extreme 2: The aircraft has been parked outside in a coastal or sandy environment, open to the weather and seasonal factors


In our view, most aircraft will be somewhere in between these extremes. Furthermore, storage procedures will have varied in accordance with the airline's view of the likely duration of the grounding period as it commenced.


Most manufacturer programs start with the question, "For how long will the aircraft be stored?"


If the answer was 60 days but this subsequently becomes 180 days, the program will have not started in the most appropriate way. That is not to say the aircraft will be unairworthy and, of course, one cannot turn back the clock. It does however mean further checks and inspections will probably be required.


In the context of returning aircraft to service from extended storage due to the Covid-19 pandemic, the UK's Civil Aviation Authority (CAA) issued a safety notice 27th July (SN-2020/013). The European Union Aviation Safety Agency (EASA) also published advice on 20th July and the CAA supplied broader guidance dealing with the subjects of mental health and human factors as aircraft, technicians and pilots, cabin crew, air traffic controllers and ground handlers prepared to return to work.


Returning aircraft to service is therefore not simply a case of performing technical tasks; it is vital each airline coordinates the technical process with its flight and maintenance operating crews, its regulatory authority, maintenance organisation, continuous airworthiness manager and the aircraft's financier or lessor to ensure compliance with its contract's commercial terms.


Some examples of problems found after extended parking periods are highlighted in the CAA's safety notice and include:


  • Engine borescope ports found loose
  • Flap access panel found missing but with screws in place after a ferry flight for a maintenance check
  • Crew unable to start engines due to circuit breakers pulled with no log book entry to alert others
  • Depletion of brake accumulator pressure
  • Multiple Airworthiness Directive and Never Exceed Period overruns
  • A rejected take off due to unreliable speed indications. Insect larvae contamination of pilot system found even though covers in place during storage


Evidently, the aircraft re-entry process includes numerous essential steps and requires careful management so delays and further loss of revenue are avoided. IBA's experienced technical team can offer their comprehensive understanding of the global aircraft fleet to provide valuable support.


With over 33 years' aviation industry knowledge, IBA operates globally and our Technical Managers are qualified to inspect and understand any and all modifications, airworthiness directives and service bulletins implemented on aircraft during the grounding period, with special focus on:


  • Storage, preservation and de-preservation, maintenance of records and evidence of maintenance activities conducted towards re-entry into service
  • Inspections of the replacement of any excessively reworked panels, modifications and assembly to ensure adequate electrical bonding
  • Fuel contamination
  • Inspection and understanding of service bulletins and airworthiness directives on wiring bundles


IBA has experienced licensed engineers with a detailed, expert understanding of its new generation systems and we have in country resource to travel to any of the storage airports or locations where aircraft have been stored.


Please do get in touch with Peter Walter or Guljar Lehri if you're an owner, lessor, operator or financier of aircraft and would like to discuss issues relating to returning aircraft to service or storage and maintenance.


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