Crashes in the News - Thread

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bmcj

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Any info about a light plane that crashed into a California house. Parachute found but pilot fatality. House was occupied and on fire but occupants escaped.
Not much. It was a Cirrus that had just taken off from Cable Airport. Single pilot was killed, but those on the ground were unhurt. The parachute was deployed, but it was unclear if it was deployed in flight (and probably too low) or if it was post-impact.
 

sotaro

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jedi

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it is in my area but I have no clew. I suspect it is a one off with 1/2 VW.

A call to the departure airport (S36 Norman Grier) only added that the pilot is out of the hospital and confirmed that the engine did quit.
 

Wanttaja

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Just wondering what plane this is, the aspect ratio is high. Single seater strut supported high wing, yellow, "ultralight" 2 cylinder opposed 4 stroke. Just curious.
Pilot is a member of my EAA chapter. IIRC, the ultralight was a one-of that he bought several months back. I believe it did have a half-VW.

Ron Wanttaja
 

Doggzilla

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The 737 Max has the same exact issue, the trim cutoff switches are identical but with different purposes.

Almost everyone I talked to responded so hostile that they would literally make things up to try and call me a liar and to avoid admitting it was true.

Then a Boeing engineer confirmed my assumption, and yet people still won’t admit it was correct. Even after one of their own engineers confirmed it.

Incompetence through arrogance.
 

radfordc

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Interesting article, but someone should tell the author that they aren't in journalism school any more and doesn't need to be so 'wordy'. Skip every other paragraph and the read goes quicker - with no lost content. :p
If you were getting paid "by the word" what would you do?
 

pwood66889

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davidb

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The 737 Max has the same exact issue, the trim cutoff switches are identical but with different purposes.

Almost everyone I talked to responded so hostile that they would literally make things up to try and call me a liar and to avoid admitting it was true.

Then a Boeing engineer confirmed my assumption, and yet people still won’t admit it was correct. Even after one of their own engineers confirmed it.

Incompetence through arrogance.
With no hostility or arrogance, I am trying to understand your concern as well as trying to understand Boeing’s justification. I’m just an operator. The non Max cutout switches are labeled different than the Max. I was able to confirm that the left cutout switch does disable the thumb switches and the right switch does not. The right cutout switch is labeled autopilot and presumably cuts out autopilot trim.

When I have access to a Max again, I’ll test what the left and right switches actually cut out since they are labeled primarily and secondary.

The point is still mute from an operator standpoint because the procedure for any trim malfunction is to turn off both cutout switches. There is no operator procedure for turning off just one of the switches.

Another mystery is why the thumb switches are actually two split switches. One’s thumb actuates both (split) switches simultaneously, so what is the reason for the split? If you just move one half of the split switch, the trim doesn’t move. Perhaps the engineer you have contact with can provide some historical reasoning?
 

Doggzilla

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From what he wrote, he checked the records and they show that a modification to the switches was approved between 737NG and MAX.

Yes, pilots are not trained to use the NG switches properly, but any smart pilot would have learned about them as you have.

In fact, one of the Ethiopian MAX pilots attempted to turn on the left trim switch after the defective manual trim jack jammed, but the switch also sent power to the MCAS as well, allowing it to force trim down even further and guaranteeing a crash.

If it had been wired separately like the NG his actions would likely have allowed him to restore trim.
 

Vigilant1

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In fact, one of the Ethiopian MAX pilots attempted to turn on the left trim switch after the defective manual trim jack jammed . . .
This is a complex topic and we are all working from information that is incomplete. Popular press accounts often use incorrect terms. Let's not confuse the issue with our own imprecise language.
What is the "defective manual trim jack"? The plane has one jackscrew for the horizontal stabilizer, and there's no indication it was defective. The jackscrew is designed to be turned using either the trim wheels or the electric trim. If you are making an assertion that the design of that system or part was deficient, that is a different thing than saying a part is defective.
"Left trim switch" is what? Are you referring to the electric trim cutout switch (located on the pedestal below the throttles) or something else?

I'm just trying to understand what you are asserting here.
 
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davidb

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From what he wrote, he checked the records and they show that a modification to the switches was approved between 737NG and MAX.
That part is not in dispute, but there is a probable reason behind the modification that doesn’t support your assessment.

As I understand it, there are two trim motors that turn the jack screw. The autopilot uses only one but the manual electric trim (thumb switches) uses both. The thumb switches command a higher trim rate than the autopilot trim rate. All the previous automatic trim functions like speed trim only needed the slower autopilot trim rate. The new MCAS high AoA function probably needed the higher trim rate that both motors provide. I suspect the new labeling of the cutout switches has more to do with the MCAS using both motors.

The only proper use of the cutout switches is to cutout both. There is simply no trim malfunction that could be addressed by only cutting out one regardless of how they are labeled or wired.
 

Doggzilla

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That still doesn’t excuse the design flaw, as they could have just not wired the left switch to the MCAS and left the pilot with full control.

They should not have wired MCAS to both switches.
 

Heavy Iron

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The non Max cutout switches are labeled different than the Max. I was able to confirm that the left cutout switch does disable the thumb switches and the right switch does not. The right cutout switch is labeled autopilot and presumably cuts out autopilot trim.
Correct, all 737-100 through 737-900 the left cutout switch kills the main electric trim and the right switch kills the autopilot trim.

When I have access to a Max again, I’ll test what the left and right switches actually cut out since they are labeled primarily and secondary.
The two switches now are essentially in series and either switch will kill both main electric trim and autopilot trim. This was most likely done for 2 reasons: 1- to provide redundancy, if the left switch breaks when you are trying to stop a main trim runaway the second switch will provide the cutout function eliminating a single point failure risk. 2- there has only been a single motor on the stab trim actuator assembly since the NG was introduced so what would have been the point the point in maintaining 2 separate switches to that have no redundancy? I think the new functionality on the MAX is much better.

As I understand it, there are two trim motors that turn the jack screw. The autopilot uses only one but the manual electric trim (thumb switches) uses both. The thumb switches command a higher trim rate than the autopilot trim rate. All the previous automatic trim functions like speed trim only needed the slower autopilot trim rate. The new MCAS high AoA function probably needed the higher trim rate that both motors provide. I suspect the new labeling of the cutout switches has more to do with the MCAS using both motors.
See above, there were two motors from the 737-100 through the 737-500 one main electric trim, one autopilot. Now only a single motor does both all the work on the 737-600 through the 737MAX.

If it had been wired separately like the NG his actions would likely have allowed him to restore trim.
They did restore the trim just before the end, have you seen the preliminary report with the FDR readouts? They had difficulty with the manual trim wheel, restored the electric trim, trimmed nose up (although they never went anywhere near to getting the aircraft back in trim) and after the 5 second time delay which disables MCAS after electric trim use MCAS trimmed nose down again more than they had just trimmed nose up and the impact was shortly after.

I wish I had time tonight to look up the exact details again for you, I haven't read the preliminary report again since it was released in early April. I am busy this week teaching a 737-200 course (I am a maintenance instructor with 25 years line maintenance experience on 737-200 through MAX) but I will try to dig up some more details next week.

There is too much incorrect info about what happened (read the report, don't listen to any media) and about MCAS (again, ignore all media here). The switches are NOT wired to MCAS, the switches stop the electric trim from operating the jackscrew. MCAS is just a bit of software running in the FCC's (Flight Control Computers), there are other bits of software that also can operate the trim system without pilot input and the 737MAX certainly is not the only aircraft in the world that lets computers move flight controls.

Another mystery is why the thumb switches are actually two split switches. One’s thumb actuates both (split) switches simultaneously, so what is the reason for the split? If you just move one half of the split switch, the trim doesn’t move. Perhaps the engineer you have contact with can provide some historical reasoning?
The split switches are to prevent a single shorted switch from causing a trim runaway. 1 half of the switch starts the motor, the other half engages the clutch which connects the motor to the gearbox that drives the jackscrew.

Ron
 
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