Managing Aircraft Lease Agreements and Maintenance Reserves - Aircraft Storage

Posted by on in Regulatory
  • Font size: Larger Smaller
  • Hits: 286

Sofema Aviation Services considers the generic requirements associated with the Storage and Return to Service of Aircraft during or prior to leasing. 

Forthcoming Training Notification - Managing Aircraft Lease Agreements and Maintenance Reserves - 3 Days - Bangkok, Thailand 9 am to 5 pm from November 25th to November 27th, 2019. Please see the following link for details:


Please treat as a Generic Guide only as in each case it is necessary to consult with the Type Certificate Holders (TCH) Approved Maintenance Data.


Always consider that High Humidity, as well as Cold & Wet environments, can have quite negative effects on stored airframes, so factor this into your considerations and ensure correct steps are taken.


▪ Installation of protective coverings and closing of all external openings (except drains).

▪ Perform parking and mooring procedures.

▪ The Aircraft should be periodically washed.

Note - May be a repetitive task depending on environmental considerations.

▪ Protect all Flight Deck & Cabin Windows to prevent erosion.


▪ Inspection of seats and carpet for moisture/mildew (Particularly if stored in humid environments).

▪ Follow preservation requirements for lavatories and water systems. 

▪ Ensure optimum ventilation throughout the Cabin by opening monuments, closets, cabinets, and interior doors to prevent the possibility of mildew.

Landing Gear

▪ Install all landing Gear Locks.

▪ Strut to be serviced, Oleos Protected & Tyres Inflation Checked & Periodically Rotated.

Fuel System

▪ Take regular samples and periodically perform Biobor (Microbiological inhibitor).

Operational Checks

▪ Ensure adequate procedures to transition the aircraft from preservation to a state acceptable for engine operations and operational checks of systems, back to the preserved state.

▪ Ensure Primary & Secondary Flight control systems operated. lubricated and exercised by cycling.

▪ Operate Air Conditioning & Hydraulic Systems.

Engine/Auxiliary Power Unit (APU):

▪ Engage with procedures to operate the engine & APU in accordance with an established interval.

▪ Perform complete preservation of the engine & APU.


▪ Perform periodic opening & closing of all circuit breakers.

▪ Perform servicing task on Batteries.

Note - Batteries deteriorate very quickly so special care should be taken (Capacity Check should be required before Return to Service (RTS).

▪ Remove all batteries from emergency equipment such as a megaphone, flashlights, power supplies for emergency lights, emergency beacons. 

Return to service procedures

In addition to all aircraft maintenance manual (AMM) procedures to return the aircraft to serviceability ensure that the aircraft is assessed for compliance with AD’s and Alert Service Bulletins plus any other calendar-driven tasks.

In general, the following procedures should be followed:

a) Review both the current status of the aircraft to the aircraft maintenance program (AMP) to ensure compliance with required tasks, Airworthiness Directives (AD’s), life limited components (LLP), certification maintenance requirements (CMR), avionics databases, etc.
b) Perform any other inspections and operational checks, as deemed necessary, based on the amount of time the aircraft was in storage and the environment to which it was exposed.
c) Perform operational check flights or test flights prior to return to service.

Sofema Aviation Service and Sofema Online offer regulatory and vocation training both online and within the classroom environment. For details or enquiries please email or

Last modified on