From a purely operational point of view, all aircraft would be working round the clock and generating revenue throughout their life. In the real world some need to be parked or stored for short, or even long periods of time.
Special COVID-19 update
Customer Services teams are working hard to adapt maintenance recommendations and support customers who have fleets partially or wholly grounded during this period.
The situation calls for exceptional measures and reactivity to provide pragmatic support to operators during this difficult period, while keeping the highest levels of safety.“Never in the history of aviation have airlines had to ground so many aircraft, so quickly. They need help to reduce the huge and sudden maintenance workload, and to ensure a quick return to service when required,” explains Gilles de Cevins, head of maintenance programmes and services.
In addition to increasing its support teams and giving recommendations to customers, Airbus is providing technical justifications and solutions for maintenance burden reduction. This includes extending calendar intervals for scheduled maintenance tasks and reducing the frequency of periodic ground checks from every week to every two weeks.
Airbus has published technical data via Operators Information Transmissions (OITs). Technical queries about these should be addressed to Airbus Customer Services through the TechRequest tool on AirbusWorld, selecting the Scheduled Maintenance domain and the Parking & Storage topic.
Parking and storage - what’s the difference?
‘Parking’ usually means the aircraft is taken out of operation for up to six months. Sometimes longer spells of parking mean coming out of a flight-ready condition, but it is more usual to carry out the regular light maintenance needed to preserve a ‘ready to go’ state which allows a rapid return to service. Every week over 100 aircraft are parked for periods which exceed 14 days.
‘Storage’ generally applies when a rapid or unexpected return to service is unlikely and the planned period out of service is up to two years. In these cases airworthiness can be maintained but more preferable is a reduced maintenance schedule combined with preservation activities, such as sealing and greasing.
Why store an aircraft that could be earning?
Aircraft are sometimes referred to as ‘revenue generators’. It is common for them to enter commercial service within days of delivery to operators and a key aim of fleet planning is to safely maximise the time each aircraft spends in the air carrying passengers or freight. Parking or storing an aircraft is an expensive option but there are sometimes compelling reasons to do so.
Time away from operations, such as when waiting for maintenance activities, isn’t unusual and some operators have business models which include being less busy at particular times of year. Offering holiday-related travel to regions where a seasonal climate is part of the destinations’ appeal might mean anticipating a regular ‘down-season’. Reducing flight frequency or closing some routes and then parking or storing part of the fleet makes better financial sense than flying aircraft with too many empty seats. Aircraft are also sometimes taken out of service while awaiting return to the leasing company that owns them. Getting all the relevant dates and activities involved to coincide perfectly can be difficult so a short period of parking can be a practical solution.
However, unplanned events can also create a need for parking or storage, usually in circumstances where the operator has little choice but still needs to protect their asset. These can range from technical issues which can’t be resolved quickly to an aircraft being grounded by the authorities while a long way from its base. Financial issues can also create a need for storage, such as bankruptcy, outstanding fuel bills, lack of ground and cabin staff or pilots, and abandonment of aircraft owned by lessors.
Regional or global crises can lead to a complete or partial collapse in the usual infrastructure needed to support aviation. Humanitarian disasters, widespread health or sanitary problems, extreme economic or political events; whatever the reason, parking or storage might be the only viable option available to aircraft operators caught in the middle of such events.
Why protection is key
Once an aircraft is out of service the likelihood of issues caused by the wear and tear of routine flying is reduced. Nevertheless, without proper protection a host of new threats to the condition of the aircraft can emerge depending on the climate and conditions the aircraft is stored in. Weather can cause problems. If rain, snow, salty air, dust or sand enter air ducts, they can degrade or contaminate the mechanical parts they come into contact with. Extremely high winds can also cause damage to an aircraft that might be considered safe and stable in normal circumstances. High humidity, lightning strikes and volcanic ash also require special consideration.
Protection against unwelcome ‘passengers’ is also vital. It only takes weeks for rodents, birds and insects to cause serious damage to a previously pristine cabin with seats, carpets and wiring all vulnerable particularly if a nest is established. Returning to service without an expensive and time-consuming deep-clean and repair operation is unthinkable. In extreme cases, infestation can also lead to blocked ducts, some of which could have safety repercussions – again thorough checks and remedial actions take time so avoiding the problem is the best solution.
Help! - Requests from around the world
A wide variety of natural phenomena can threaten stored or parked aircraft. Customer Services teams are often asked for advice on dealing with potential issues, some of which have a distinct regional flavour.
Salty and humid conditions require extra protection.
With up to 80 million locusts in the central area of a swarm the need for extra caution is clear. Moving aircraft into hangars and sealing ducts and potential entry points is crucial.
In winter, temperatures can reach below 40°C. In ‘deep freeze’ cold of this nature, some plastic and rubber derived parts can become brittle so care is needed.
Asia and Northern Europe:
Heavy rain and high humidity can cause mildew inside the aircraft. Without careful sealing, extreme water levels can even cause cabin flooding leading to litres of water pouring out at the end of the storage period. However, sealing must be done correctly to ensure that evaporation is still possible, thus preventing mould.
AMM (Aircraft Maintenance Manual) procedures cover mooring of aircraft in winds up to 75 knots. Severe typhoons have winds of at least 80 knots while super typhoons are defined by winds of at least 100 knots. Advice varies according to specific circumstances but it can include moving aircraft into hangars - or out of them if the buildings themselves are at risk. Filling fuel tanks can add extra weight to the aircraft while removing plastic sheeting prevents it from catching the wind and becoming a ‘sail’ which drags the aircraft.
Overall it is fair to say that, depending on location and on seasonal and operational conditions, the exact procedures for storage or parking vary. However, protecting the aircraft against contamination, mechanical degradation or damage is always essential.
Aircraft should be parked or stored in clean and serviceable condition. Measures should be taken to clean the cabin, galleys and cargo, service all the systems, protect the exposed areas, and carry out the periodical checks. Anticipation is also vital. Use experience and knowledge of the environment as a guide, to take appropriate actions for cold weather, ventilation, mooring, and ensuring that sufficient fuel is in the tanks for water draining or APU (auxiliary power unit) operation and engine runs.
AMM or Maintenance Procedure tasks exist to prepare an aircraft for parking/storage and return it to service and these should always be followed.
Asking the right questions
When deciding whether to park or store an aircraft, you should check requirements carefully. An out-of-operation aircraft can be maintained with an approved maintenance programme. Consult the AMM to find procedures and check which are mandatory.
Seven frequently asked questions:
ISI 10.00.00003 GUIDELINES FOR APPROPRIATE ACTIONS
Is it necessary to park or store an aircraft before a scheduled maintenance check, working party or cabin refurbishing?
Check the guidelines regarding your specific circumstances.
ISI 10.00.00004 PARKING or STORAGE EXTENSION
What can I do when the parking or storage period has expired?
Normally after two years an aircraft must return to operation before going back into storage. This should become a deviation in the future and there will be no need to re-fly if the aircraft is not required by the operator.
ISI 10.00.00005 AIRCRAFT SYSTEM INTEGRITY
Is it possible to remove parts from an aircraft that is parked or stored?
Parked aircraft should be flight ready – batteries can be removed to preserve them as they can be quickly reinstalled. Other items can be removed in specific conditions, for example some of the fire extinguishers in the cabin aren’t necessary for a flight without passengers. However, removing parts for parking is highly restricted.
In stored aircraft, it is more common for major components to be removed. Engines, APUs, flaps and computers all have high value and can be transferred to in-service aircraft. The best solutions often depend on the planned storage time. Operators have some flexibility and should check with Airbus if in doubt. It can become a costly process if an aircraft needs to return to service when major parts have been removed, so operators should be clear about the storage mode and duration before making decisions.
ISI 10.00.00006 SCHEDULED MAINTENANCE CONTROL
What is the starting date to be used to calculate future ground checks?
All dates must be calculated based on the last flight date. This rule applies even if an aircraft is initially parked then moves to storage, or if it needs two months of maintenance then is parked.
ISI 10.00.00007 TASKS CALENDAR
How does a parking or storage period influence the scheduled maintenance?
Scheduled or planned maintenance must still be done, but may be postponed until the end of a parking/storage period if operators have agreement from their local authority. If an aircraft is in short-term parking mode, it is advisable to do scheduled maintenance when due, to avoid delays on return-to-service.
ISI 10.00.00008 ENGINES & APU ON WING
Who shall I ask questions to related to engines and APU?
Operators need to refer directly to the engine and APU manufacturers in line with legal requirements.
ISI 10.00.00009 ASSISTANCE and ISI 10.00.00010 COVER DEVIATIONS
How can Airbus support me regarding aircraft parking and storage?
Operators can log a request in the Airbus TechRequest too, for advice, deviation options, and overdue maintenance where aircraft needs to be flown to a specific maintenance base or to new owner.
Operators who supply full and accurate information to Airbus can be supported with documents confirming that procedures have been followed – these can be a requirement for airworthiness authorities.
Support and responsibilities
Airbus deals with several requests for support every day and offers advice as well services. It can evaluate specific situations to help ensure the safety and serviceability required for an easy return-to-service. Operators are responsible for ensuring correct and complete information for Airbus when preparing validation from their authorities.
As for any maintenance actions, parking and storage have to be approached like a planned maintenance check. All the regulations and standard practices apply. Preparation, traceability and proper execution of the maintenance tasks are essential for a safe and uncomplicated release back into service.
Keeping the AMM current
By reporting back to Airbus, operators can help keep the AMM up-to-date in the light of experience and evolving techniques. This happened, for example, when operators explained that the aluminium covers being used to prevent fabric fading inside the cabin were actually causing paint discoloration around the windows. A new technique was then developed to resolve this issue.
Scheduled Maintenance seminars
These include some information on critical situations for parking and storing, aircraft waiting for dismantling, or needing leasing company acceptance for flight, aircraft on standby and more
Back to service
To return an aircraft to service all the required maintenance must be carried out. This includes all scheduled maintenance, daily and weekly servicing when needed, and the restoration of any defects which may have arisen during the period of storage or parking. Everything required to bring the aircraft back to operational standards and ensure safe use is essential. Calendar items as well as mandatory items, Airworthiness Directives, All Operator Telex, shelf-life equipment, and inspections due must be included. Upon release into service the aircraft must be fully airworthy in every respect.
Whatever the circumstances, when parking or storage is the right solution for an aircraft it is wise to prepare in advance and strongly advisable to refer to the latest recommendations and guidelines in
the AMM, in-service information and technical follow-up documents.
Making full use of Airbus support as early as possible to evaluate specific needs, avoid unplanned deviations and anticipate costs will also help. Keeping delays and costs down means thinking through storage rental but also planning maintenance to avoid overdue work causing a backlog which ultimately delays return-to-service.
The most crucial piece of advice is to get in touch early. This helps all parties and allows the best possible experience of a potentially complicated situation. Poorly planned and handled storage or parking can lead to aircraft being prevented from returning to operation when required and the consequences for revenues can be serious.