737 quiz

[yawdamper]

Folks,

 

while waiting, I thought it would be nice to have a thread with some quiz questions regarding the 737 where you won't typically find the answer in the FCOM.

 

• Sitting in the cockpit with everything set up, how would you know if the spoilers extend when rotating the control wheel? Remember, the EFIS 737 doesn't have flight control displays. And no peaking outside the window!
• Assuming you have all static ports blocked (no altimeter). You took off, flew the numbers according to QRH and at some point levelled off. What ways can you think of to get an estimate of your altitude (MSL or AGL)? (Aircraft was just painted and someone did a really bad job during the preflight :-) )
• The F/O's course selector is not responding to changes. What could this indicate?
• If the airplane symbol appears in the lower right corner of the EHSI - what does this indicate?
• The CRT wears out and suddenly there is a color loss in the EADI. What implications could this have on landing in bad weather?
• You are having a very bad day (obviously!) and now all 4 CRT's are black/white (complete loss of color). Any implications?

Let's start with that :-)

 

Regards

YD

 

 

[Paterpilar]

• The CRT wears out and suddenly there is a color loss in the EADI. What implications could this have on landing in bad weather?

 

I can't see the ILS glideslope magenta point?

[cod360]

• A TR deployment in flight. Would a recovery be possible?

[therocketman93]

Alright, where's Jan? 

[Vantskruv]

Sitting in the cockpit with everything set up, how would you know if the spoilers extend when rotating the control wheel? Remember, the EFIS 737 doesn't have flight control displays. And no peaking outside the window!

Hydraulic pressure change?

 

Assuming you have all static ports blocked (no altimeter). You took off, flew the numbers according to QRH and at some point levelled off. What ways can you think of to get an estimate of your altitude (MSL or AGL)? (Aircraft was just painted and someone did a really bad job during the preflight :-) )

1. Calculating time from takeoff and the medial climbrate (climbrate * time), you should get AGL.

2. If you have a OAT (or similar) and probably some ISA dev and temperature at ground, you may calculate the the altitude MSL. I'm just guessing here, as I've not learned the procedure for this, but it should be possible.

 

The F/O's course selector is not responding to changes. What could this indicate?

Not a clue

 

If the airplane symbol appears in the lower right corner of the EHSI - what does this indicate?

Not a clue

 

The CRT wears out and suddenly there is a color loss in the EADI. What implications could this have on landing in bad weather?

Not a clue, I'm a analog guy.

 

You are having a very bad day (obviously!) and now all 4 CRT's are black/white (complete loss of color). Any implications?

Are there no analog backup instruments in the aircraft? Fly accordingly. Though maybe not able ILS approach...

 

 

Folks,

 

while waiting, I thought it would be nice to have a thread with some quiz questions regarding the 737 where you won't typically find the answer in the FCOM.

 

• Sitting in the cockpit with everything set up, how would you know if the spoilers extend when rotating the control wheel? Remember, the EFIS 737 doesn't have flight control displays. And no peaking outside the window!
• Assuming you have all static ports blocked (no altimeter). You took off, flew the numbers according to QRH and at some point levelled off. What ways can you think of to get an estimate of your altitude (MSL or AGL)? (Aircraft was just painted and someone did a really bad job during the preflight :-) )
• The F/O's course selector is not responding to changes. What could this indicate?
• If the airplane symbol appears in the lower right corner of the EHSI - what does this indicate?
• The CRT wears out and suddenly there is a color loss in the EADI. What implications could this have on landing in bad weather?
• You are having a very bad day (obviously!) and now all 4 CRT's are black/white (complete loss of color). Any implications?

Let's start with that :-)

 

Regards

YD

 

[montoya_110]

 

• The CRT wears out and suddenly there is a color loss in the EADI. What implications could this have on landing in bad weather?

 

maybe there is something wrong with equipment cooling?

[Litjan]

Dang, this is serious stuff. Here is my guess, without looking at the AMM and being corrupted by flying Airbuses for 4 years :

• Sitting in the cockpit with everything set up, how would you know if the spoilers extend when rotating the control wheel? Remember, the EFIS 737 doesn't have flight control displays. And no peaking outside the window!

Hydraulic Quantity indication decreasing (as fluid gets caught in the extended cylinders)

 

• Assuming you have all static ports blocked (no altimeter). You took off, flew the numbers according to QRH and at some point levelled off. What ways can you think of to get an estimate of your altitude (MSL or AGL)? (Aircraft was just painted and someone did a really bad job during the preflight :-) )

Either get into the ACMS and do an Alpha lookup of geometric GPS altitude (MSL). This would also work with a handheld GPS like your mobile phone, if you have an APP for that.

You could use your weather radar with a tilt of 0. The beginning of the "ground return" in NM divided by 3.3 is approximately your altitude AGL in thousands of feet.

Another way is to get a radar station with altitude readout (military) to scan you, or to have a friendly plane come up and fly alongside ;-)

The last possibility is to depressurize the airplane and use cabin altitude indication.

 

• The F/O's course selector is not responding to changes. What could this indicate?

Some mechanical malfunction of the transducer, or the MCP locked up (usually goes along with altitude going to 50.000 and the altitude alert blaring...). It could also be an electrical failure of a certain bus (no idea off the top of my head which one)

• If the airplane symbol appears in the lower right corner of the EHSI - what does this indicate?

Never seen that conciously or heard of it.

• The CRT wears out and suddenly there is a color loss in the EADI. What implications could this have on landing in bad weather?

The colour is required for autoland, because the FMA is written in "green" and if that colour fails, you could not verify the autopilot status during a low-vis approach.

• You are having a very bad day (obviously!) and now all 4 CRT's are black/white (complete loss of color). Any implications?

This is mostly due to lack of airflow (equipment cooling). The CRT´s might shut down at a later stage, depending on how the internal temperature develops. Try to re-instate airflow by going to an alternate ventilation system.

 

 

Let's start with that :-)

 

Regards

YD

[Litjan]

So... what are the correct answers? Great idea, by the way!

[yawdamper]

Hi All,

 

ok let's go:

 

• Sitting in the cockpit with everything set up, how would you know if the spoilers extend when rotating the control wheel? Remember, the EFIS 737 doesn't have flight control displays. And no peaking outside the window!

Hydraulic pressure change? - with the EDP and EMDP running, you shouldn't see a noticeable drop in pressure.

Hydraulic Quantity indication decreasing (as fluid gets caught in the extended cylinders) - yupp

 

• Assuming you have all static ports blocked (no altimeter). You took off, flew the numbers according to QRH and at some point levelled off. What ways can you think of to get an estimate of your altitude (MSL or AGL)? (Aircraft was just painted and someone did a really bad job during the preflight :-) )

GPS alt readout - yupp

WX radar trick - yupp (actually learned this one at LFT!)

Cabin depressurization - yes, I suppose :-)

Military radar - yupp

Formation flying - yupp, in VMC.

Calculating time from takeoff and the medial climbrate (climbrate * time), you should get AGL. - ah but without static ports, your climb rate will be unknown. The IVSI will jump around based on IRS vertical acceleration data, but without a change in static pressure, it will settle down at 0 FPM gradually.

If you have a OAT (or similar) and probably some ISA dev and temperature at ground, you may calculate the the altitude MSL. I'm just guessing here, as I've not learned the procedure for this, but it should be possible. - works as long as the atmosphere is behaving according to ISA. An inversion layer will tell you you have descended below your departure airport elevation :-)

 

I can think of two more methods (one obvious).

 

• The F/O's course selector is not responding to changes. What could this indicate?

Mechanical failure - yupp

MCP freeze - yupp

Elec bus failure - yes, in fact it's the battery bus that powers the right MCP CRS selector

 

• If the airplane symbol appears in the lower right corner of the EHSI - what does this indicate?

Answer: indicates a frozen display. It's worth a try to switch both EFI to the opposite side.

 

• The CRT wears out and suddenly there is a color loss in the EADI. What implications could this have on landing in bad weather?

 

I can't see the ILS glideslope magenta point? - the glideslope indicator will still be visible, it just won't be magenta.

The colour is required for autoland, because the FMA is written in "green" and if that colour fails, you could not verify the autopilot status during a low-vis approach. - yupp!

 

• You are having a very bad day (obviously!) and now all 4 CRT's are black/white (complete loss of color). Any implications?

This is mostly due to lack of airflow (equipment cooling). The CRT´s might shut down at a later stage, depending on how the internal temperature develops. Try to re-instate airflow by going to an alternate ventilation system. - yes, this indicates both SGs are overheating. According to my notes, both EADI/EHSI displays will shut down after 90 minutes.

 

 

Ok a small follow up regarding the 'depressurize cabin to get alttiude estimate' trick: assuming you are somewhere at FL350 (ok bad idea to depressurize). Your static ports suddenly clear up and the IVSI is indicating that you are descending at 1500 fpm. Assuming the outflow valves are fully open and the cabin has had enough time to reduce pressure differential to 0 PSI. Both packs are off. What would the cabin rate indicate?

• 1500 fpm cabin descent?
• Higher than 1500 fpm descent rate?
• Lower than 1500 descent rate?

 

And why?

 

Regards

YD

Edited January 13, 2016 by yawdamper

[SkyCoyote]

Assuming you have all static ports blocked (no altimeter). You took off, flew the numbers according to QRH and at some point levelled off. What ways can you think of to get an estimate of your altitude (MSL or AGL)?

Check temperature to boil water.

Edited January 13, 2016 by SkyCoyote

[Litjan]

 

Ok a small follow up regarding the 'depressurize cabin to get alttiude estimate' trick: assuming you are somewhere at FL350 (ok bad idea to depressurize). Your static ports suddenly clear up and the IVSI is indicating that you are descending at 1500 fpm. Assuming the outflow valves are fully open and the cabin has had enough time to reduce pressure differential to 0 PSI. Both packs are off. What would the cabin rate indicate?

• 1500 fpm cabin descent?
• Higher than 1500 fpm descent rate?
• Lower than 1500 descent rate?

 

And why?

 

Regards

YD

 

My first guess was that the descent rate would be lower, since all the air has to rush in through the little outflow valve opening, but there are fairly big negative-pressure relief panels on the fuselage that make sure that the pressure differential can never be negative. So my guess would be: Also 1500fpm.

 

Cheers, Jan

[Litjan]

Check temperature to boil water.

 

Drop someone from the pilots window and time how long until impact!

[yawdamper]

Check temperature to boil water - But then you'd need to depressurize the cabin, so it might be just a tad easier to read the gauge on the overhead.

Drop someone from the pilots window and time how long until impact! - How do you know when the pilot hits ground? You could jump with him and then you'd know how high you were... But now the aircraft is left without pilots....

 

Coming back to 'What would the cabin rate indicate?'

 

Well, I've never tried it (yet!) but my vote would be: the indicator would show a much lower descent rate since it is calibrated in sea-level-equivalent fpm. The pressure change for a 100 foot altitude difference at sea level is much higher than at 35000 ft, so even if the aircraft is descending at 1500 fpm, at sea level the pressure difference would be much lower. Of course the cabin itself would descend at a similar rate (minus any dynamic effect) as the aircraft, but I was specifically asking for the cabin rate indicator

 

Standing by to getting shot down...

 

YD

[mgeiss]

As long as your DME and radio compasses are working, I guess you could calculate your altitude by tuning two VOR/DME stations and then use triangulation based on the current DME and direct CRS to the stations. Of course that would only be feasible at higher altitudes, as the error is rather big (probably greater than  +/- 1500ft). It would be more of an estimation.

 

Or - if time permits - you could just overfly a DME station, but I don't know how accurate the DME reading is when being directly overhead.

 

 

Side note: If this was an Airbus quiz, I guess the answer to all those questions would be: you're f***ed

Edited January 14, 2016 by mgeiss

[Litjan]

Check temperature to boil water - But then you'd need to depressurize the cabin, so it might be just a tad easier to read the gauge on the overhead.

Drop someone from the pilots window and time how long until impact! - How do you know when the pilot hits ground? You could jump with him and then you'd know how high you were... But now the aircraft is left without pilots....

 

Coming back to 'What would the cabin rate indicate?'

 

Well, I've never tried it (yet!) but my vote would be: the indicator would show a much lower descent rate since it is calibrated in sea-level-equivalent fpm. The pressure change for a 100 foot altitude difference at sea level is much higher than at 35000 ft, so even if the aircraft is descending at 1500 fpm, at sea level the pressure difference would be much lower. Of course the cabin itself would descend at a similar rate (minus any dynamic effect) as the aircraft, but I was specifically asking for the cabin rate indicator

 

Standing by to getting shot down...

 

YD

 

Hmm, interesting. I didn´t think about that variometers are calibrated to a certain altitude. But that would mean that regular variometers (like on high performance piston acf) are also only accurate at a specific altitude? However they are designed to be used at a big range - from sea level to 20.000+ feet. There has to be some sort of compensation - pressure gradient per 1000´ of altitude is much smaller at 20.000 than at MSL. I imagine there is some sort of transmission that is affected by static pressure, thereby compensating different pressure gradients.

 

Here is an interesting post that also describes how the orifice corrects for pressure and temperature changes:

 

http://www.theairlinepilots.com/forum/viewtopic.php?t=898&sid=1c06fdf9e75cfb858b57227f8e136307

 

Of course it is unknown to me wether such a (more expensive) instrument is also built into the cabin VSI. It really only needs to be accurate from 10.000 to 0 feet, if you want to plan the cabin descent rate to match the aircrafts descent path. This might be needed when using the Standby mode or even manual AC or DC mode.

Above 10.000 feet cabin altitude you really only care about the absolute pressure change per minute, as this directly affects what you and the passengers "feel" as you try to get the cabin under control again.

 

Cheers, Jan

Edited January 14, 2016 by Litjan

[daemotron]

Side note: If this was an Airbus quiz, I guess the answer to all those questions would be: you're f***ed

 

Not really... some of the failures described are specific to the 737 (F/O course selector, airplane symbol), so it doesn't make any sense trying to transfer these questions to a 'bus (and btw: I assume you thought about an A320). CRT failures can occur on older models, though.

 

Concerning the obvious method for AG estimation: descend until your radar altimeter tells you 

[mgeiss]

I know, i was just kidding.

I just don't like busses.