At my airline the B737NG normal procedures are very clear - some things such as flight deck door are clearly "first flight of the day" and other things such as fire tests are "each crew change". Perhaps my operator has modified the Boeing FCOM to make it clear - suits me fine.
But on the topic of non-SOP system testing, I have two anecdotes of interest:
1. Our 737-3/400 series required a test of the Emergency Lighting system during preflight. When we moved to B737NGs the Emergency Lighting system test was removed - it became an engineering function during overnight checks. One particularly thorough Captain found it difficult to adjust to the change at first - if we've been checking it all these years for good reason, why stop now? So he continued to check the lights until lo and behold they failed the test one time. Aircraft significantly delayed and instead of a congratulations from the Chief Pilot for his vigilance above and beyond, he got invited for tea and bikkies to explain why he unnecessarily delayed a flight for conducting non-SOP system checks. His protestations of the potential danger of an aircraft flying around with U/S emergency lighting did not impress the Chief Pilot one bit. He was told to follow the procedures or find another job.
2. The fire tests are normally performed by the F/O. One Captain decided to change things around one day and did it himself (actually permitted by the FCOM but not normally done). The Master Fire Warning press-to-cancel button on the LHS MCP failed to cancel the fire bell. The F/O side still worked, as did the bell-cancel on the centre console. But the DDG said no dispatch and the aircraft went off to the hangar for 24 hrs, and pax significantly delayed. The switch in question had possibly been U/S for weeks or months, who knows.
Where do you draw the line? Good question. I'm not a SOP-nazi - sometimes SOP's are declared contributing factors in investigations, true. The are usually changed accordingly after the event. But Boeing have more information and statistics at their fingertips when they design SOP's than I do. Sometimes operators change SOP's because they think they know better, sometimes pilots do too. Sometimes they are right, sometimes they are wrong, sometimes it is of no consequence. But for a pilot, I think, generally speaking, going outside of SOP's is only defendable when you genuinely believe safety is at risk. A truly subjective assessment, sometimes. An attitude of "well it worked on the DC3, so I ain't changing" may not be relevant or defendable.
Just food for thought when you make a decision to test things outside SOPs - it may improve safety, it may not. It also may affect the schedule or your career. Where you choose to draw the line may depend not only on your personality but also on the personality of those who employ you. And these are just anecdotes. I love the Tech forum on PPRuNe, there is some great advice here, but you need to sort the appropriate advice from the inappropriate. That's what experienced pilots do.
Last edited by Derfred; 16th Aug 2015 at 08:28.