Date: 201604
Local time of day: 0601-1200
Location: ZZZ.Airport, US
Aircraft: Citation Excel (C560XL)
Flight plan: IFR
Flight phase: Parked
Aircraft component: Main Gear Tire
Reporter function: Captain; Pilot Flying
Reporter qualification: Flight Crew Air Transport Pilot (ATP)
Human factors: Situational Awareness
Anomaly: Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: Routine Inspection
Result: General Maintenance Action
Contributing factors: Aircraft; Company Policy; Human Factors; Procedure
Primary problem: Ambiguous

Narrative: I had a main tire that was getting close to the wear limits; and I was watching it closely. We had a few hours on the ground; so I decided to go out and take a closer look at the tires while we were there. As I was out there; a FBO maintenance crew pulled up in their vehicle; and informed me that Maintenance Control had asked them to come look at my tires; and check the tire pressures. They said that Maintenance Control was aware that our tire was getting close; and that they were tracking it. The FBO mechanics determined that the tire was still serviceable; and proceeded with checking the tire pressures.The mechanics measured the nose tire pressure at 115; which is considered 'under inflated' per the maintenance manual. It can be serviced; and continued operation is allowed; but the maintenance manual requires an entry into the aircraft logbook with the recorded tire pressure; and a recheck of the pressure 24 hours later. I left the mechanics to finish what they were doing; and went inside; but noticed they never actually went inside the airplane and documented the low tire pressure in the logbook.I asked the mechanics later if they were going to document the low tire; and informed them of the required maintenance manual steps for a nose tire pressure of 115 PSI. They looked at me a bit quizzically; and then looked up the maintenance checklist online for further guidance. The newly re-written maintenance checklist directs them to call Maintenance Control for a nose tire reading under 123; so they called for further instructions. To my surprise; Maintenance Control directed them to change the nose tire; and the main tire that they had been tracking for wear. When we returned to the aircraft the next morning; we found that they actually changed all three tires overnight.While I am encouraged by the proactive maintenance; it didn't appear that there was any work order generated to conduct the pressure check of the tires. This may have led to improper maintenance procedures. Because the mechanics were not using the checklist; the tires were simply serviced to proper levels; without any entry to the aircraft logbook. Had I not witnessed the tire pressure check and informed the FBO maintenance crew of the requirements; it is my belief that no further action would have been taken. It also made me wonder; how many times is this happening [here]; or other FBOs; while the crew is at the hotel? Had I not been out at the airplane at the time; I would not have known that the tires were even serviced.The update to the maintenance checklist has certainly been an improvement. In this case; however; it seems that the maintenance checklist was bypassed for a more informal 'servicing request'. Without the Checklist; there is a great possibility for error with no formal way to trap those errors.It seems Maintenance Control asked the FBO maintenance crew to evaluate the tires; and service them without a work order. It is my belief that the FBO crew would have simply adjusted the tire pressures to correct level; and went on about their business without documenting anything. Checklists keep us safe in the air; and on the ground. The newly written Checklist should be used anytime the airplanes are serviced; to ensure proper maintenance procedures are conducted.




Synopsis: CE-560XL Captain reported that his company has a new maintenance checklist to ensure that all actions taken to maintain the aircraft are entered into the log book. It appears to the Captain; that Maintenance Control and the mechanics that do the work are not familiar with it however.