A number of business jets–more than 3,000 by some estimates–are sitting idle on the ramp as their owners wait for the economy to improve. According to Rich Schuller, founder of Schuller Aerospace Services International of Scottsdale, Ariz., there could be trouble brewing for those owners. “Aircraft owners who fail to comply with applicable turbine-engine-preservation procedures will discover it results in significant expense and potentially serious aircraft devaluation,” he told AIN.

Schuller said many operators have an out-of-sight, out-of-mind perspective, believing that if they aren’t flying the airplane there’s nothing to worry about. However, those who do not comply with the OEM’s turbine-engine-preservation procedures, and the respective guaranteed engine hourly programs contracts, will be exposed to high costs to correct the condition outside the contract.

“The M50 bearing materials in turbine engines are a good example,” he said. “When they’re not lubricated they’ll develop micropitting in certain atmospheric environments. This micropitting can destroy the bearing surface, leading to expensive and catastrophic failures at high rotational speeds. Even accelerated Soap samples will not provide sufficient warning to prevent an impending failure.”

According to Schuller, one of the contributors to owner cost shock is well known to mechanics. “Whenever you disassemble an engine to inspect the bearing surfaces, inevitably a lot more will be discovered that requires heavy maintenance compliance,” he said.

Schuller said he often hears of aircraft that sit unused for an extended time following operational and mechanic cuts. Without professional oversight, required engine-preservation duties are not accomplished, resulting in what most guaranteed hourly engine programs classify as “abuse.”

“My best advice for operators who are going to let their aircraft sit for an extended time is to read your contract. In most cases, engine care compliance requires that the enrolled equipment follow the engine-preservation requirements in the OEM’s maintenance manual. Failure to comply leads to engine removal and return to an approved/authorized MRO facility for an expensive inspection,” he cautioned.

“Commercial carriers manage fleets, so they are sensitive to such issues and are well attuned to the requirements of strict preservation requirements; [that is not the case] in our fragmented industry. My advice is to make absolutely certain that the defined maintenance actions described in the appropriate manuals are complied with by a certified aircraft mechanic or MRO facility. If in doubt, contact the engine OEM customer support or the guaranteed-cost provider,” he said.

Schuller emphasized the importance of contacting the OEM customer-support representative to ensure compliance. If the operator fails to conduct, or record, required maintenance during extended down times an abuse violation can follow. “When that happens the owner-operator will be liable for the repair costs and test-cell certification to return the engine to an airworthy status and restore coverage under the insurer’s contract terms. That will be expensive,” he said.