Responsibilities in aircraft airworthiness

According to the Aviation Act and the EU Continuing Airworthiness Regulation, the owner is responsible for the airworthiness of the aircraft. If a user has been recorded for the aircraft in the aircraft register, the owner’s responsibility is transferred to the registered user. The responsibility may also be transferred to the renter, if agreed in the rental agreement of the aircraft. From the point of view of the pilot, the aircraft can be considered airworthy if the documents carried on board are valid and there is no visible damage to the aircraft which has not been appropriately moved. From the point of view of the owner, the matter is more complicated.

An aircraft is only airworthy if all of the maintenance measures specified in the aircraft maintenance programme (AMP) have been carried out on time. It is not necessary to record the next scheduled maintenance, i.e. specify when the airworthiness ends, in the log book of an aircraft in private use. This means that the pilot has no way of knowing whether the aircraft is airworthy or not. The owner is responsible for the aircraft staying on the ground, if it is not airworthy.

The aircraft is not airworthy if the maintenance requirements of the aircraft include an oil change every 120 days, and it has been more than 120 days since the last oil change (and the provision of the maintenance certificate). Similarly, the aircraft is not airworthy if the maintenance requirements include a brake fluid change every four years, and it has been more than four years since the last brake fluid change, even if the annual maintenance had been carried out one week prior.

Contrary to common misconceptions, the maintenance organisation is not responsible for the airworthiness of aircraft. The maintenance organisation is only responsible for the airworthiness of the maintenance work that was commissioned by the owner and that they have performed. The owner is responsible for having all the maintenance work performed on time, i.e. ordering all necessary maintenance work and keeping records of all maintenance work in the service log. This is referred to as so-called continuing airworthiness management. If the owner has only ordered an annual maintenance service, but not the maintenance measures scheduled for a four-year period, the maintenance organisation shall only perform the annual maintenance service. The customer may want to order the maintenance jobs over four years from another provider or at another time, and the owner is responsible for the aircraft not being flown until all of them have been completed.

The aircraft owner is also responsible for ensuring that an aircraft maintenance programme (AMP) has been drafted for the aircraft (including a summary of all of the maintenance requirements applied to the aircraft) as well as keeping the AMP up-to-date. A separate maintenance programme is required because the list of maintenance tasks in the aircraft maintenance handbook does not usually cover all of the required maintenance. Authorities may, for example, issue airworthiness orders that require repeated inspections. A piece of equipment with specific maintenance requirements, such as an emergency locator transmitter (ELT), may have been installed into the aircraft. Changes requiring specific maintenance instructions may have been made to the aircraft.

The changes may require changes to the maintenance task list in the aircraft maintenance handbook. If the maximum take-off mass (MTOM) of the aircraft is changed, for example, it may affect the structural fatigue strength intervals. Similarly, replacing the propeller with another type of propeller naturally requires the replacement of the maintenance requirements to suit the new propeller. These are all compiled in the maintenance programme, based on which a maintenance schedule monitoring plan for the aircraft can be drafted. The maintenance monitoring plan will display the validity of the aircraft’s airworthiness and how much time is left before each of the scheduled maintenance tasks. Maintenance schedule monitoring allows the owner to see which maintenance tasks should be included in the next scheduled maintenance, to ensure that the validity of the aircraft’s airworthiness is sufficient.

The Continuing Airworthiness Regulation provides the owners of Part-ML aircraft in private use the opportunity to approve the maintenance programme themselves. Approving of the maintenance schedule and taking responsibility for the approval will alleviate bureaucracy and reduce costs, but requires the owners to be even more knowledgeable about the maintenance requirements.

Here, the owner’s responsibility means real responsibility which may, in extreme cases, lead to liability for damages from accidents, if the owner’s negligence or carelessness can be proven to have contributed to the occurrence of the accident. The practical application of the regulation remains to be seen.

The owner may transfer the responsibility for the drafting and management of the maintenance programme as well as the management of continuing airworthiness to an approved continuing airworthiness management organisation. This requires that an agreement be made with the organisation in question. It may be helpful to employ the services of a mechanic or other person presumed to be an expert in continuing airworthiness management, but the responsibility for ensuring the airworthiness management expertise of such a person and their work lies unambiguously with the owner.

An approved continuing airworthiness management organisation (CAMO) has an operating licence issued by an authority in an EU Member State. The operating licence has a member state ID of two letters, the abbreviation CAMO and usually a four-digit licence number (e.g. FI.CAMO.0001). The licence number may also read CAO for combined airworthiness organisation instead of CAMO.

Aircraft registration and documents to be carried on board during flight

According to the Aviation Act, the owner must notify any changes to the to the authorities within 14 days. The Finnish Transport and Communications Agency may prohibit the use of the aircraft if this notification has not been submitted.

If the aircraft remains in the register for the same Member State, the airworthiness documents will remain valid even if the owner changes. The new owner must, however, draft a new maintenance programme for the aircraft, taking into account the requirements derived from the type of operation and updating the information of the owner and the person in charge of airworthiness management.

If the registration country changes, the owner must apply for a new and as well as a , if the aircraft requires a noise certificate, from the authorities of the new registering Member State. Mandatory insurance specified in the EU regulation on insurance requirements for air carriers and aircraft operators must be taken out for the aircraft.

The aircraft pilot is responsible for operating the aircraft in accordance with the approved flight manual, performing pre-flight inspections to detect any non-compliance in airworthiness, as well as reporting any non-compliance in airworthiness to the airworthiness manager and/or person or organisation maintaining the aircraft. The aircraft must not be operated unless the non-compliances have been rectified or postponed for correction in accordance with an approved list of minimum equipment.

The non-compliance of a Part-ML aircraft in private use may be postponed by the aircraft pilot in terms of non-mandatory equipment, as well as with permission from the airworthiness manager (=CAMO/CAO or owner) for other non-compliance.

Any non-compliance that puts flight safety at considerable risk must be repaired before flying the aircraft again.

The person or organisation maintaining the aircraft is responsible for performing the tasks ordered by the continuing airworthiness manager and for the airworthiness of the jobs they have done. The person or organisation maintaining the aircraft must provide a maintenance certificate for their work, itemising the tasks that have been performed, any tasks that were ordered but not completed and which instructions were followed when performing the tasks.

The itemisation must be sufficiently precise to avoid any confusion as to which measures were performed when examining the maintenance log in the future, because the airworthiness manager and the person performing the airworthiness inspection should be able to determine the aircraft’s airworthiness based on the maintenance log. The airworthiness documentation for the parts and components used must be provided to the manager of continuing airworthiness, because they have the obligation to keep them.

According to the Continuing Airworthiness Regulation, the person or organisation maintaining the aircraft must have access to valid applicable maintenance instructions, and only these instructions must be used when performing maintenance tasks. The instructions include instructions verified by a competent authority or EASA, airworthiness directives (ADs) as well as instructions published by type certification holders, supplemental type certification holders or other design organisations approved in accordance with EASA Part 21, i.e. the type certification regulation. The operating licence of the design organisation follows the format EASA.21J.(licence number).
The aircraft’s airframe, engine and propeller may have type certifications, meaning that these may have type certification holders specified in the type certification regulation. Various changes made to the aircraft’s type design may have supplemental type certifications (STCs), the holder of which may not be the same as the holder of the type certification. All of the above must have a permit issued by the design organisation. In addition to this, an approved design organisation may design small changes and repairs within the framework of their permit. This means that maintenance instructions published by them are approved. Anyone can design small changes and repairs and apply to have them approved by the authorities. Instructions verified by the authorities, such as these, are also approved after the approval has been granted.

Please note that component manufacturers often publish maintenance instructions for their components. These manufacturers do not usually have the operating licence of a design organisation, meaning that they do not assume the same responsibility for the quality of the instructions or their suitability for a certain type of aircraft, in particular. That is why these instructions may not be used in aircraft maintenance, unless the holder of the type certification or other design certification refers to these instructions in their own instructions. In this event, the design certificate holder assumes responsibility for their content. Usually, the design certificate holder provides separate maintenance instructions, which include the maintenance instructions for all of the components within the design.

The design approval holder − i.e. the type certificate, supplemental type certification or change or repair approval holder − is responsible for the continuing airworthiness of the design from the time the certificate was issued until the last aircraft in accordance with the design has been decommissioned. This means that the design approval holder must produce the instructions required for the maintenance of the continuing airworthiness of the aircraft, monitor the product’s user experience and update the instructions, if necessary.

The Continuing Airworthiness Regulation requires all parties involved with airworthiness to report any factors putting aviation safety at risk to the design approval holder and the authorities. Any other difficulties with maintenance should be reported to the design approval holder to allow for improvements.
If the type approval holder loses their design organisation approval, meaning that they are no longer able to carry out their obligations (and no other organisation assumes responsibility for the type design), the authorities must take action to revoke the type certification. After the type certification has been revoked, the use of the aircraft now of uncertified type may be continued in private use according to the instructions specified in the Specific Airworthiness Specifications (SAS), which have replaced the Type Certificate Data Sheet (TCDS). An aircraft with a revoked type certification may not be used for commercial aviation.