So to consider firstly the difference between AD’s & SB’s (there is in fact a significant difference). AD’s are mandatory and SB’s are essentially optional and it is up to the operator to evaluate and decide.
Why do we have SB’s?
Every SB tells a story of either compensation for under performance or an opportunity for a chargeable enhancement. It is through the process of SB embodiment that aircraft are able to remain at the forefront of reliability and it is the balance of SB Embodiment versus Return on Investment that usually drives the decision making process.
The operator or Lessee is essentially mandated to perform all required maintenance to an aircraft in accordance with the various requirements as driven by the regulator (For example Airworthiness Directives – AD’s ) and is required to have a policy to review Service Bulletins, however note that there is no obligation to actually perform any SB’s (Even so called mandatory SB’s are not in fact “mandatory”)
Where is the Risk?
The risk is related to the anticipated asset value which is expected at the point of lease return compared to the actual asset value, which may be achieved.
The ultimate owner of the aircraft “the lessor” of course expects the underlying value of an asset to diminish over time this should normally be within an expected range of behaviour.
As well as cyclical and industry factors for example a particular airframe going out of fashion (who wants an A340-500 these days :)) or the price of fuel going through the roof.
Lessee induced deterioration also plays a considerable role a poorly cared for aircraft will off course achieve a lower asset value.
Additional considerations will include the following :
– The general status of the Airframe Structural and the forthcoming Inspections
– The SB status of the aircraft and components
– Time to the next scheduled “C” check”
– Time to the next Landing Gear Overhaul
– The Current Performance Standard of the Engines
– Status of Engine Life Limited Parts (LLPs)
– Status of the Auxiliary Power Unit (APU)
As far as the Lessor is concerned mitigating the risk is related to the size of the maintenance reserves together with the anticipated maintenance status.
Obviously an airframe or engine which has recently received a recent maintenance overhaul will have a higher market value than one, which is due for maintenance, whether it will exactly equate to the value of the maintenance check remains to be seen.
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