Boeing 737 Max8 Aircraft Crashes and Investigations [Part 3] 36

[Sparweb]

This is the continuation from:

thread815-445840
thread815-450258

This topic is broken into multiple threads due to the long length to be scrolled, and many images to load, creating long load times for some users and devices. If you are NEW to this discussion, please read the above threads prior to posting, to avoid rehashing old discussions.


Some key references:

Ethiopian CAA preliminary report

Indonesian National Transportation Safety Committee preliminary report

The Boeing 737 Technical Site

No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF

 

[Alistair_Heaton]

Even though I have zero interest flying an airbus the fact that the qf flight was mentioned made me dig a bit further into the incidents with control issues with them.

They are very thought provoking. Like or not fly by wire is going to be a feature of all clean sheet new types in some form or other.

The airtanker incident was a particular example of pilot unintended collosal screw up.

Just looking at the Miami air overrun sad thing with these overruns is the lesson never seems to be learned. After this macas issue I am pretty certain history won't repeat itself. If we could only find a way of stopping pilots going of the end of the runway with a perfectly serviceable aircraft. Its a credit to the engineering these days it rarely results in fatalities.

 

[Kwan]

I do not think the task of using the second AOA as a verification is trivial (IMHO). A side slip will cause the two AOA's to disagree. Likely this can be programmed but then the aircraft would need a side slip indicator. It's a tough problem to solve.

 

[Alistair_Heaton]

They all have a slip indicator, its an output from the AHRS which is laser gyros.

http://www.b737.org.uk/flightinstsmax.htm

If you look at the PFD picture and where it says CMD is the roll indicator just below the white triangle pointer there is a rectangular box. That's the slip indiactor and works the same way as a fluid analog ball slip indicator.


Normal ops you don't use it much on jets, turbo props we use it every time we change the power or airspeed.


The jets use it when an engine fails. If you don't have slip indication you will end up with cross controls and huge amounts of drag resulting. Every change in power and speed single engine requires the rudder to be re-trimmed the only instrument you can use is a slip indicator. rudder, roll elevator is the order you trim the three axis in.


To be honest side slip affects the airspeed more than it does the AoA readings.


It is actively frowned apon these days to use sideslip to get rid of energy. Its another lost skill.

 

[VEBill]

Sideslip "...frowned upon....to get rid of energy. Its another lost skill."

Useful skill when gliding into Gimli.

Canadian pilots seem to be experts at gliding long distances in fuel-less airliners.

 

[VEBill]

Boeing statement (BBC).

 

[Sparweb]

It is actively frowned upon these days to use sideslip to get rid of energy. Its another lost skill.

While flight training in a Cessna 172, on my second solo cross-country trip, I was coming back in to Calgary but must have missed a call-out from the terminal. I had been cleared to approach but not yet cleared to descend for visual landing. I had also been cleared to descend only to 4000 feet (not runway elevation 3550 feet). After a pause where I completed the base leg without descending, I requested confirmation of clearance to descend for landing. No reply. I began to wonder if I was splitting hairs. All previous approaches to Calgary YYC I had been given separate clearances for each step to approach, join the circuit, descend, and land. But one could assume that clearance to approach implies clearance to land... I chose to maintain 4000 feet until cleared to do so, in case there was traffic below me, turned for final approach, and repeated my request.

Finally, as I crossed the fence, the clearance to descend for landing finally came, and by now the only way I was going to touch the runway was a very steep side-slip. I pulled the power to idle, ignored the flaps and just cranked the rudder to the stop, leveling the wings with aileron in a way I had only previously done to demonstrate the meaning of "crossed controls". I was also glad nobody was in the plane to see me do this.
I shed 500 feet shockingly fast, using up 1/4 of the 2-mile long runway 32. Rolled to a stop far past where I would normally turn off to a taxiway, and made a long trundle back to the school's hanger that much longer.

I suspect I had done something earlier in the flight that irked the controller, but I never found out what. YYC was never very accommodating of the student traffic. All the schools have since abandoned that airport.

No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF

 

[Alistair_Heaton]

Some good news today though for Boeing, the 777-9 had its first engine run with the GE9X engine. No problems reported.

Lets just hope they don't have any issues with the folding wing tip's.

I used to teach sideslip to my ppl students but the youngsters that I work with that have gone through the large sausage machine flight schools have never heard of it.

Alot of tail draggers with large engines use it as standard on approach so the pilot can see the runway.

In distant memory's cessna has an issue with you doing it with certain flap settings because the vortex off the wings disrupts the airflow over the tail. Piper tomahawk or traumahawk as some like to call it that I did most of my teaching in had zero issues doing it

The tommy airspeed indicator used to read zero while you were doing it. And due to its alleged stalling characteristics most other instructors wouldn't do it and thought me crazy to even attempt it. Mind you they wouldn't spin the tommy either.

 

[Alistair_Heaton]

Spar any chance of you setting up the next part, this thread is getting a nightmare to look at on portable devices.

 

[Kwan]

Thanks for the feedback Alistair!

I should have stated an angle of slideslip (AOS) indicator. This would measure the angle of aircraft to the relative wind. Similar to the AOA measurement. I'm not an aero loads guy. I grow crack and perform static analysis but use the CFD loading for finite element models. The CFD reports show oil lines (representing airflow) on the aircraft. I can see that it can change AOA but this may be insignificant as you noted.

I took some flight instruction and did several solo flights. Then school and money got in the way and I never finished my private license. Bleeding altitude with sideslip is fun! My instructor taught this, but it was years ago. He would also open the window on cross wind landings just before touch down to simulate gusts. He was a fantastic instructor.

 

[rb1957]

S'Web … you could have always done a missed approach "clearance to land too late, going around". If you'd pranged it, it would've been your fault.

another day in paradise, or is paradise one day closer ?

 

[Sparweb]

RB,
You know me, so you must know I enjoyed every moment of it!
AH,
Your memory serves you well. No flaps permitted during a slip in a 172, which I took care not to do. With full rudder you are already quite face-down to the earth. Extending flaps even by mistake would only add to the discomfort.

Enough about slipping. Time for snipping...

No one believes the theory except the one who developed it. Everyone believes the experiment except the one who ran it.
STF

 

[Sparweb]

THIS THREAD IS CLOSED.

Please continue the discussion at the new thread:
thread815-454283

Thank you everyone for this enjoyable discussion.
This topic is being broken into multiple threads due to the long length to be scrolled, and many images to load, creating long load times for some users and devices.