B737 Stabiliser Trim Checks
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B737 Stabiliser Trim Checks
"When I was on the 707......." (sorry), during the pre flight checks, there was a requirement to check the Stab Trim internal braking mechanism.
The drill was to run the stab at maximum speed, release the trimmer, and count the number of revolutions after releasing the switch. The limit was three quarters of one turn and it usually stopped immediately!
Now to today's modern 737 which I am assured, has the same mechanism!
If I run the 737 (EFIS) stab trim at max speed - with the flaps deployed and on the ground of course! - and then release the switch, what is the limit and where is this limit found in the Maintenance Manual (reference please if possible).
Thanks,
NIL
The drill was to run the stab at maximum speed, release the trimmer, and count the number of revolutions after releasing the switch. The limit was three quarters of one turn and it usually stopped immediately!
Now to today's modern 737 which I am assured, has the same mechanism!
If I run the 737 (EFIS) stab trim at max speed - with the flaps deployed and on the ground of course! - and then release the switch, what is the limit and where is this limit found in the Maintenance Manual (reference please if possible).
Thanks,
NIL
Join Date: Jan 2001
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Maint manual ref..27-41-00 p513-514.
Flaps up...If free movement is more than .5 of a turn you must replace the main elect trim actuator.
Flaps down...If free movement is more than 2.5 turns you must replace the main elect trim actuator.
Flaps up...If free movement is more than .5 of a turn you must replace the main elect trim actuator.
Flaps down...If free movement is more than 2.5 turns you must replace the main elect trim actuator.
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There seems to be a few of these “supplementary” checks in circulation. Personally I always check the stab trim cut-out by trimming forward and moving the control column aft & then vice versa as part of the cockpit preparation. It is part of the prep for an air-test, but not a revenue flight (Why?) yet it only takes a few seconds.
S & L
S & L
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Ok Static, lets discuss the wisdom or otherwise of these checks.
Safety is the most important issue here. The checks are not unsafe to do, they are recognised checks, in the above cases by maintenance or by crews before air-tests, done at the commanders wish before a flight. They may discover a potentially unsafe condition; that has to be good.
The cockpit preparation scan is very detailed and you will find that most companies have slightly different versions of it. Even the Boeing version has changed over the years, so if you think you are doing the definitive version then check what date your company manuals last had an input from Boeing.
When I was in the RHS I saw that different Captains had their own couple of “extra checks” such as standby power check, wing-body overheat test, EIS LED test, TAT test etc, etc. These were all in addition to and did not replace any checks required by the company. None of these caused me any concern with regard to standardisation as it all came under the umbrella of
“Flight Deck Preparation…………Completed”.
Now that I am in the LHS and have many more thousands of hours, I too have developed my own way of completing the Flight Deck Preparation. It is still well within the bounds of the company SOP’s but is probably subtly different from other Captains, as theirs will be from each others. It is not non-standard or maverick but simply applying a bit of airmanship from my experience to check things to my own satisfaction before getting airborne with passengers.
Rgds
S & L
Safety is the most important issue here. The checks are not unsafe to do, they are recognised checks, in the above cases by maintenance or by crews before air-tests, done at the commanders wish before a flight. They may discover a potentially unsafe condition; that has to be good.
The cockpit preparation scan is very detailed and you will find that most companies have slightly different versions of it. Even the Boeing version has changed over the years, so if you think you are doing the definitive version then check what date your company manuals last had an input from Boeing.
When I was in the RHS I saw that different Captains had their own couple of “extra checks” such as standby power check, wing-body overheat test, EIS LED test, TAT test etc, etc. These were all in addition to and did not replace any checks required by the company. None of these caused me any concern with regard to standardisation as it all came under the umbrella of
“Flight Deck Preparation…………Completed”.
Now that I am in the LHS and have many more thousands of hours, I too have developed my own way of completing the Flight Deck Preparation. It is still well within the bounds of the company SOP’s but is probably subtly different from other Captains, as theirs will be from each others. It is not non-standard or maverick but simply applying a bit of airmanship from my experience to check things to my own satisfaction before getting airborne with passengers.
Rgds
S & L
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I have to agree somewhat with Static. Of course you are entitled to have some "personal SOP's". It's exactly the way S&L describes it: well within company SOP's. But, there are a lot of people making things more difficult for themselves then necessary.
Studying the maintance manual is, to my opinion, a step to far. You don't want to be overloaded with information, knowledge and procedures in some situations. I've always been told Keep It Simple and Stupid ( or someting similar
).
We are drifting away from tye topic I guess..........
Happy 2002
Studying the maintance manual is, to my opinion, a step to far. You don't want to be overloaded with information, knowledge and procedures in some situations. I've always been told Keep It Simple and Stupid ( or someting similar
).We are drifting away from tye topic I guess..........
Happy 2002
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S&L,
I see your point. I knew the reasoning behind it prior to your reply.
When I was still in the RH seat, I also flew with different types of commanders, displaying all sorts of different behaviours. As an FO you can learn al lot from these different approaches to various situations. Then you can decide which you want to adopt as yours when the time comes to move to the left seat.
One of the first things I decided to do is: Stick to the SOP`s. Not necessarilly because they are always the best in every situation, but mainly because that way you keep your FO in the loop. He knows what you`re doing, instead of constantly having to think by himself: "what the *** is he doing now again?" This improves the safety of the flight more than a couple of extra checks here and there. However harmless your excursions from the SOP`s might be, you force the guy in the seat next to you to spend energy to adapt to your way of doing things as opposed to the last commander he flew with and the next one.
On top of that: if you really feel strongly about certain checks; get your company to incorporate them in the cockpit prearation procedure. That way everyone can benefit from your ideas.
Ofcourse as a captain you should always feel free to do things outside the book/rules/law, whenever the situation asks for it. However in my opinion cockpit preparation doesn`t fit into this category.
Regards,
Static
I see your point. I knew the reasoning behind it prior to your reply.
When I was still in the RH seat, I also flew with different types of commanders, displaying all sorts of different behaviours. As an FO you can learn al lot from these different approaches to various situations. Then you can decide which you want to adopt as yours when the time comes to move to the left seat.
One of the first things I decided to do is: Stick to the SOP`s. Not necessarilly because they are always the best in every situation, but mainly because that way you keep your FO in the loop. He knows what you`re doing, instead of constantly having to think by himself: "what the *** is he doing now again?" This improves the safety of the flight more than a couple of extra checks here and there. However harmless your excursions from the SOP`s might be, you force the guy in the seat next to you to spend energy to adapt to your way of doing things as opposed to the last commander he flew with and the next one.
On top of that: if you really feel strongly about certain checks; get your company to incorporate them in the cockpit prearation procedure. That way everyone can benefit from your ideas.
Ofcourse as a captain you should always feel free to do things outside the book/rules/law, whenever the situation asks for it. However in my opinion cockpit preparation doesn`t fit into this category.
Regards,
Static
