Gulfstream G200 (IAI 1126 Galaxy)
Confusion; Troubleshooting
Aircraft Equipment Problem Less Severe; Deviation / Discrepancy - Procedural Maintenance; Deviation / Discrepancy - Procedural Published Material / Policy
Flight Crew Took Evasive Action; General Maintenance Action
Procedure; Aircraft
During preflight; I noticed that the oxygen valve on the lower oxygen tank was 'pointing' opposite the top tank indicator. In order to be sure of the valve position one has to bend down close to the lower window (upper tank is more easily read); otherwise valve indication can be ambiguous. The top cylinder valve selector was toward the green tick mark; while lower tank valve selector was pointing toward the red mark. Maintenance was notified and the cover over the tank valves was removed. Both valves on the tanks were in the correct position; open; and safety wired as such. It was the red/green markings on the lower cylinder window that were incorrectly painted on the tank valve cover; which was remedied by Maintenance. Apparently there are only a few aircraft with this oxygen setup with two cylinders; most of our aircraft have only one. The cylinder valves have ON/OFF markings on them clearly marked when the cover is removed. However; those placards cannot be read through the sight window during preflight with the cover on. Pilots have to rely on painted markings on the cylinder covers to determine valve status. Maintenance should make a point in confirming the correct markings on the covers. On this aircraft they are opposite: Top bottle pointing to the aft of the aircraft is open; bottom bottle valve pointing forward is open. The arrangement on the other dual bottle aircraft should also be confirmed as they may not be consistent across the fleet.
A G200 pilot noted that the two oxygen bottle valves on his aircraft could not be easily viewed and because the top and bottom valve indicators pointed in opposite directions; determining the valves position and the availability of oxygen was difficult.