Thread Tools
Apr 13, 2019, 02:08 PM
pushing the envelope
rcgroupie's Avatar
Thread OP
Discussion

Do we Trust the FAA to Regulate sUAS?


For those of you who have not been paying attention, the FAA allegedly Type Certified the 737 MAX allowing the base model to have a single Angle of Attack (AOA) sensor force anti-stall elevator trim adjustment. It appears they may have been in bed with Boeing. Why would we trust them to regulate toy RC models with big (trustworthy?) players like Amazon Prime Air, Walmart and GoogleX heavily involved with the regulatory process?


For those not familiar, AOA sensors on the MAX is like a small weather vane on the side of the jet. The budget option used in a lot of third world countries allows for a single sensor to fly the plane into the ground by adjusting the elevator trim screw jack. It is dumbfounding that anyone would ever imagine what is known as a 'single point of failure' in a commercial passenger jet. If you look at hydraulic systems, for example, you will see redundant, even triple redundant lines, with check valves to shut off broken lines, and with backup hydraulic pumping systems. So Boeing says the stall prevention system can be disabled by the pilots in case of issues. Apparently the pilots of Ethiopian Air did just that, but the system apparently automatically re-engages if it isn't satisfied with the flight profile. Another disturbing fact is that it is a jack screw, implying some delay in changing the trim. So if there is ice, debris, a mylar balloon, wiring harness or connector issues on ONE sensor it becomes impossible to save the aircraft. Another thing is that apparently there is/was no simulator for pilots to train in that scenario. Apparently there is an FBI investigation into Boeing and the FAA over this issue. My personal opinion, and I say this without prejudice, is that responsible parties from both Boeing and the FAA should spend a long time in jail if this is true.


Consider the current disparity in what it takes for a 10 year old kid to fly a camera multi-rotor vs. what it takes for a realtor to take a picture of a home for sale 'commercially'. Consider that lawnmowers kill or maim thousands of people annually, but are completely unregulated.
Sign up now
to remove ads between posts
Apr 13, 2019, 02:20 PM
FA34HM3YC7
Rhea's Avatar
So what is your solution to all of this then?
Apr 13, 2019, 02:54 PM
pushing the envelope
rcgroupie's Avatar
Thread OP
Quote:
Originally Posted by Rhea
So what is your solution to all of this then?
My solution as in another thread is for the model aircraft hobby to be self-regulated, similar to the way several groups regulate SCUBA diving.
Apr 13, 2019, 03:17 PM
FA34HM3YC7
Rhea's Avatar
I have read some of your other posts.
I agree that the FAA regulations will not solve the problem that the agency imagines.
As for the hobby regulating itself--that's the way it has been for years and it worked well.
However, there is a new hobby that has been lumped into the original and we can see that the "one size fits all" does not work.
My solution is to treat MY hobby as it was originally and fly as I always have. If I have to be tested in order to enjoy my hobby so be it. It really won't change my hobby.

I have some other thoughts but will stop here and just enjoy my hobby as I always have.
Apr 13, 2019, 04:48 PM
Team Futaba
Silent-AV8R's Avatar
Do we trust them? Irrelevant, because there is no alternative. It's their game, their playground and their ball.
Apr 13, 2019, 06:01 PM
BFMAC Founding Member
Quote:
Originally Posted by Rhea
I have read some of your other posts.
I agree that the FAA regulations will not solve the problem that the agency imagines.
As for the hobby regulating itself--that's the way it has been for years and it worked well.
However, there is a new hobby that has been lumped into the original and we can see that the "one size fits all" does not work.
My solution is to treat MY hobby as it was originally and fly as I always have. If I have to be tested in order to enjoy my hobby so be it. It really won't change my hobby.

I have some other thoughts but will stop here and just enjoy my hobby as I always have.
I don't think FAA imagines that regulations (thru part 349 at least) will solve 'the problem' but their ramp-up approach seems pretty typical: if regs in place don't significantly resolve/abate the problem then go to more restrictive regs. Other than that small nit-pick I think our viewpoints have most in common. MA have been part of my life since before I was a teen and I don't (or don't want to) believe one-size-fits-all regulatory bundling is workable or even rational. I don't think FAA did it on their own initiative, but rather is being responsive to the lawmakers, as they are required to be.
Apr 13, 2019, 06:41 PM
Registered User
The boss of the FAA is Congress, they make the laws. The FAA writes the regulations for the laws. If we do not like the laws, we need to change Congress.
Apr 13, 2019, 07:41 PM
Registered User
Nope. Haven't registered, won't take the test, won't ask for permission to fly.

As for the MCAS, if you turn off MCAS it will turn itself back on, but if you cut out the electric trim entirely it will not turn itself back on. Apparently the Ethiopian Air pilots did this, were unable to adjust the trim with the trimwheel (not sure why), then turned it back on and let it fly them into the ground.
Apr 13, 2019, 11:25 PM
Registered User
Quote:
Originally Posted by nybbler
Nope. Haven't registered, won't take the test, won't ask for permission to fly.

As for the MCAS, if you turn off MCAS it will turn itself back on, but if you cut out the electric trim entirely it will not turn itself back on. Apparently the Ethiopian Air pilots did this, were unable to adjust the trim with the trimwheel (not sure why), then turned it back on and let it fly them into the ground.

Too much tension on the stabilizer jackscrew to manually turn the trim wheel. The tension needs to be relieved by pushing forward (down) on the yoke. Problem is, no altitude to do so. In addition, with all the attention being put on trimming the aircraft, the throttles were never pulled back, which also kept high pressures on the jackscrew assembly.
Apr 14, 2019, 04:56 AM
pushing the envelope
rcgroupie's Avatar
Thread OP
Quote:
Originally Posted by L.A.
Too much tension on the stabilizer jackscrew to manually turn the trim wheel. The tension needs to be relieved by pushing forward (down) on the yoke. Problem is, no altitude to do so. In addition, with all the attention being put on trimming the aircraft, the throttles were never pulled back, which also kept high pressures on the jackscrew assembly.
That is scary.

Apparently a couple Swedish pilots tried this in a 737 simulator last week and the forces required were overwhelming (must be a pretty good simulator). They posted it on youtube but took it down. Also, it appears the 1982 737 manual describes releasing the column, adjusting the jack screw, and then pulling back on the column repeatedly until the trim is correct. The 707 was also recovered in this manner in the early '60s. Boeing apparently dropped this vital info from the current manual.
As you mention, there might not have been enough altitude to do this regardless.


Similar to the Challenger disaster, nobody learns from history:

I got a promo photo of a Titan booster launch in the 70s and dug it out. There was a jet of flame coming out between two booster segments. The shuttle boosters copied the same O-ring design thus subject to a known issue. Don't know why they didn't fix it on the new booster, probably because of cost or scheduling. The first 'captive' O-ring booster segment was on it's way to LA for heat treatment three months prior to the Challenger disaster. It hit a bridge because the substitute driver wasn't in the left lane and was scrapped.

The segments are joined with a circular clevis on one side, and the other side is pushed in and pinned. There are O-rings on each side of the clevis to make a seal, preventing hot gasses from leaking. Pressure from combustion torques the clevis and loosens the joint. Also, the inside of the casing reaches 900 deg. F while the outside is much cooler. My calculations show the inside wanting to expand about a foot over the length of the booster, with the outside resisting. This generates a huge torque on the clevis since the modulus of D6AC steel is about 30 million. The O-rings were too cold to fill the resulting gap. This was well known to Thiokol engineers and they literally screamed at management for wanting to launch anyway. The 'captive' O-ring sits on the outside of the clevis and is squished as joint deformed.
Last edited by rcgroupie; Apr 14, 2019 at 05:49 AM.
Apr 14, 2019, 06:40 AM
Commander, U.S. Navy (Ret.)
franklin_m's Avatar
Considering that no official reports have been released, I find it fascinating that so many "experts" are commenting about things like manual manipulation of jack screws and events in simulator sessons.

Oh, and last time I checked, stabilizer trim (jack screws) on large aircraft like these were not manipulated manually.
Apr 14, 2019, 06:42 AM
Commander, U.S. Navy (Ret.)
franklin_m's Avatar
Quote:
Originally Posted by Rhea
I have read some of your other posts.
I agree that the FAA regulations will not solve the problem that the agency imagines.
As for the hobby regulating itself--that's the way it has been for years and it worked well.
However, there is a new hobby that has been lumped into the original and we can see that the "one size fits all" does not work.
My solution is to treat MY hobby as it was originally and fly as I always have. If I have to be tested in order to enjoy my hobby so be it. It really won't change my hobby.

I have some other thoughts but will stop here and just enjoy my hobby as I always have.
AMA is working hard to BRING more attention to the hobby. Latest MA talks about asking FAA for LMA up to 300lbs.
Apr 14, 2019, 06:44 AM
Commander, U.S. Navy (Ret.)
franklin_m's Avatar
Quote:
Originally Posted by rcgroupie
Apparently a couple Swedish pilots tried this in a 737 simulator last week and the forces required were overwhelming (must be a pretty good simulator).
Please cite source for this information

Quote:
Originally Posted by rcgroupie
Also, it appears the 1982 737 manual describes releasing the column, adjusting the jack screw, and then pulling back on the column repeatedly until the trim is correct. The 707 was also recovered in this manner in the early '60s. Boeing apparently dropped this vital info from the current manual.
Please cite source for this information, say a link to the 1982 737 manual and link to current manual.

Quote:
Originally Posted by rcgroupie
I got a promo photo of a Titan booster launch in the 70s and dug it out. There was a jet of flame coming out between two booster segments.
Please cite source where we can verify this image you cite
Apr 14, 2019, 07:59 AM
Commander, U.S. Navy (Ret.)
franklin_m's Avatar
Quote:
Originally Posted by L.A.
Too much tension on the stabilizer jackscrew to manually turn the trim wheel .... (empasis added)
Clearly you have no idea what you're talking about. Elevator trim jackscrews on planes of this size are not mechanically adjustable from the cockpit. Maybe in a light civilian aircraft, but not in planes of this size. There is no mechanical connection between the jackscrew and the cockpit control. It's an ELECTRICAL system. So "tension on the jackscrew" would have NO IMPACT on ability to manipulate a cockpit control.

In fact, here's a video of the jackscrew from a 737. For the record, that loud sound you hear is the ELECTRIC MOTOR!

Boeing 737NG horizontal stabilizer jackscrew cycle (1 min 40 sec)
Apr 14, 2019, 08:03 AM
Registered User
Quote:
Originally Posted by franklin_m
Considering that no official reports have been released, I find it fascinating that so many "experts" are commenting about things like manual manipulation of jack screws and events in simulator sessons.

Oh, and last time I checked, stabilizer trim (jack screws) on large aircraft like these were not manipulated manually.

Then check again. The trim wheels spin during electrical operation, because of the mechanical connection. My info is not from any arm chair type expert.


Quick Reply
Message:

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Do we need to register our EDF's with the FAA? kingneptune117 Electric Ducted Fan Jet Talk 4 Mar 24, 2018 06:44 AM
Discussion Are we debating the pending FAA/DOT regulations in a "vacuum?" kavic5150 Model Aircraft & Drone Advocacy 11 Mar 04, 2016 11:31 AM
Alert FAA/DOT Conference call regarding 2/15/15 proposed regulations for commercial sUAS Op STMPNGRND Aerial Photography 8 Feb 19, 2015 09:07 AM
Alert FAA/DOT Conference call regarding 2/15/15 proposed regulations for commercial sUAS Op STMPNGRND Multirotor Drone Talk 5 Feb 16, 2015 02:23 AM
Discussion The AMA / FAA model aircraft and sUAS regulation struggle continues in the USA RolandS888 UAV - Unmanned Aerial Vehicles 49 Mar 02, 2011 10:29 AM