A320
Flight Crew Air Transport Pilot (ATP)
Flight Crew Last 90 Days 150; Flight Crew Type 270
Troubleshooting
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Published Material / Policy; Flight Deck / Cabin / Aircraft Event Illness / Injury
Flight Crew Overcame Equipment Problem
Chart Or Publication; Aircraft; Manuals; Procedure
The airplane came from the hangar...and I noticed the Captain's Standby Navigation (STBY NAV) switch was on (showing NAV). I deselected the switch back to normal. The RADNAV page seemed to confirm this. After starting both engines; we noticed we had a Status Message on the Status page saying 'Inop System... CAT 2.' We couldn't get rid of it by cycling various things; and wrote it up and called Maintenance. After several cycled CB's and switches on the Flight Control Panel to no effect; Maintenance deferred it; which took all Auto-lands out of the picture. Maintenance said they'd never seen just a CAT 2 Inoperative before; didn't really have good guidance for it in their manuals; and weren't exactly sure of the corrective action. We had good weather at destination and figured they'd get to the bottom of it at the next maintenance station.  Shortly after takeoff; we got a Master Caution and ECAM 'NAV LS TUNING DISAGREE.' I immediately thought of the STBY NAV switch and its initial setting as well as the fact that part of the Maintenance reset procedure on the ground included manually tuning an ILS frequency on the RADNAV page to see if that would get rid of the CAT 2 message (it didn't). But RADNAV and STBY NAV were showing normal now. At a safe altitude; we looked into dealing with the ECAM. We discovered it's not in the QRH. While I was getting ready to write up a zero code; I thought I'd cycle both STBY NAV switches (Captain and First Officer) to see what would happen. Not only did this get rid of the ECAM but also the CAT 2 Status Message. We sent the write-up and an additional info message to Maintenance via ACARs explaining the event. It appeared at least; part of the airplane thought the Captain's side was still in STBY NAV even after the switch showed normal (and the RADNAV page did as well). I also mentioned in the write-up and communication that no reference was available for this ECAM in the QRH. It was my impression all ECAMs were represented in the QRH; but that obviously wasn't the case here. How many more are there like this? How would we know?
A320 Captain reported that procedures for an ECAM 'NAV LS TUNING DISAGREE' warning could not be found in the QRH. Captain questioned what other ECAM warnings are not covered in the QRH.