Date: 202104
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Aircraft: Commercial Fixed Wing
Operator: Air Carrier
Operating under: Part 91
Flight plan: IFR
Mission: Ferry / Re-Positioning
Flight phase: Parked
Reporter organization: Air Carrier
Reporter function: Pilot Not Flying; Captain
Reporter qualification: Flight Crew Air Transport Pilot (ATP); Flight Crew Multiengine; Flight Crew Instrument
Human factors: Communication Breakdown; Confusion; Situational Awareness
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: Aircraft In Service At Gate
Result: General None Reported / Taken
Contributing factors: Aircraft; Procedure; MEL; Environment - Non Weather Related
Primary problem: Ambiguous

Narrative: Prior to departure Dispatch asked us to do an APU Inflight Reliability Check which I understood to be Section XXXX.  I explained we were unable to do so because of the limited flight time and low cruise altitude.  I think there was confusion about the check they wanted us to perform.  I think they wanted a maintenance validation Section YYXX because they mentioned this Section; but it has nothing to do with the APU. The previous day Dispatch asked us to do the same thing. I was told by Dispatch on the previous day that the aircraft was going to be put back into revenue service for ETOPS and it needed an Inflight APU verification check.   Very confusing set of circumstances. As line pilots we do not do these types of Maintenance trips very often and with COVID-19 and the length of time that these aircraft have been sitting different checks need to be performed.  I had never heard of or done a maintenance validation before.  Also; under Section YYXX (O) Procedures B what are the required checks to be accomplished?  Is it an APU Inflight verification check? I entered information to Maintenance that the APU Inflight Verification Check could not be completed due to limited flight time and low cruise altitude. Also; with the maintenance validation the cruise altitude needs to be above FL200. Our cruise altitude was planned for FL220 but the rides were so bad that ATC kept us down at FL190 so we could not have done a maintenance validation anyway.  It makes sense now... there was a note on the flight plan that we were operating under FAR Part 91. I think that note was there because this aircraft needed a maintenance validation to be put back into Revenue Service. Like I mentioned very confusing for the FO and I.Not fully understanding what dispatch wanted from us.  Also not doing these types of flights often and being familiar with all of the different checks that need to be accomplished with aircraft that have been in short term and long-term storage.  I think the dispatchers are in the same positions as the flight crews as far as not being familiar with what needs to be done.Have maintenance clearly explain what needs to be done by the flight crew for these types of situations with aircraft coming out of short and long term storage.  Also; under Section YYXX what are the required checks under (O) Procedures B.?




Synopsis: Air Carrier Captain reported the crew was to conduct an in-flight check of an aircraft that had been parked during the pandemic for an extended period of time. The type of maintenance check was written unclearly.