2 stupid questions for B737

[B737MRG]

Stupid questions, but nobody that can answer ?
1) Why did they keep the 2 circle arcs on the elec panel (from the classic) when building the NG ? Many pilots tell me it was cost saving, but I disagree ; if you build a new wing, you are not going to save money by keeping some 2 USD plastic cover. I think it has to do something with certification. I think if you change one of the 4 "light grey OVHD engine failure panels", you change the type rating ?! This also explains why they have installed the SOURCE OFF amber light, which is rather useless.
2) While sleeping with my eyes open in the right hand seat (we fly both seats on 3 different airplanes...) I noticed that the AirCond Temperature indicator drops 1 up to 5 degrees when you press the Master Caution panel... It stays down until you release the Master Caution. I know this is a stupid question, but nobody that can explain why. I thought it would be a drop on the electrical bus, but MC and Temp are on a different bus...

[Golden Rivet]

Question 2

This is a recognised fault condition with the aircraft.

"Several operators have reported seeing the temperature indicator move when master caution is recalled, while the annunciator switch is being pressed. One operator has also reported the temperature indicator moving to zero when either air conditioning pack switch is placed in the HIGH position."

"During troubleshooting it was determined that high resistance between ground block GD506 and airplane structure can cause temperature indication to vary under certain conditions. There are several different ground types installed in GD506 which, when the resistance to ground is too high, will affect temperature indication."

"Operators who experience movement of the temperature indicator when master caution is recalled or during any other operation may wish to measure the resistance between ground block GD506 and airplane structure. If the measured resistance is above 0.0035, Boeing recommends operators correct the condition."

[B737MRG]

Hi Golden Rivet,

thanks for your reply. Where did you find this info, some kind of bulletin for Maintenance ?

Pat

[alexban]

1) Actually B737 ,it is cost saving.They had to change the wing,but it has nothing to do with the rest few hundreds or more components..
The wing is not the only change,but there are many items that remained the same.And it's cost saving even if you keep the buttons while changing the shirt.
Why do u think the source off light is useless? It informs u that you may be on only one source for both busses,or that something has changed from what you think it's under way on electrics operation.
And it has to be amber in color...

[B737MRG]

Hi Alexban,

Q1) is this your personal opinion or did you obtain Boeing info ? I would be really surprised if they kept the panel just for cost savings. They didn't only change the wing, but also the electrical panel just above (integrated LAD)...

[CaptainSandL]

Re Q1, I don’t know but I had always assumed it was the easiest & cheapest way to remove the gauges. It also keeps the lightplates interchangeable between the different series of 737.

There is a precedent for this, have you noticed the caption sized gap between the two RAM DOOR FULL OPEN lights on the pneumatics panel? This was the * ******* ****** light on the 1/200 series. They didn’t close the gap when the light was removed. I will leave it as a quiz for you to remember or find out what the caption said.

Regards

S&L

[Terraplaneblues]

In service a wing change is never required, but overhead panels are, operators require high rates of interchangeability for cost reasons.

Apologies for thread drift - FWD OUTFLOW VALVE CLOSED is the missing blue caption.