Control Lock Safety

When I designed the control lock for my Cessna 180, I realized that I needed to have some way to make sure than I couldn't fly the plane with it engaged. I chose this one:

I made the thing so that I can't sit on the pilot's seat with it engaged. It blocks the seat.

This works well.

Of course one reason it works well is that I never fly from the passenger side. I don't feel comfortable there and just flat won't do it. If I did once in a while, the position and design of my control lock would not be sufficient.

Today, in Aviation Week and Space Technology, there's an interesting article about a Gulfstream takeoff crash that killed several people. The two pilots started their takeoff run with the gust lock engaged. The airplane has a throttle interlock to the gust lock, preventing more than 6 of the full 40 degrees of throttle travel, but the pilots were able to defeat it by engaging the autothrottle. The gust lock remained locked.

in the article, there are two checklist items that the Gulfstream pilots neglected: one was to disengage the gust lock. The next was to do a control movement check. The pilots did neither. You might argue that failing to follow the checklist was the cause of the accident, but I'd say that allowing the autothrottle to work with the control lock engaged was certainly another; any of the three should have done the job. Also, since two of them are checklist items, if the pilots didn't bother with the checklist, they've already bypassed two of the safety measures.

One issue with the Gulfstream's control lock design is that two of the designer's ways to ensure that the locks were disengaged were of the same type, and susceptible to the same mode of failure. To use Paul Dye's term, they were similarly redundant. The throttle interlock was a dissimilar redundancy.

On our simpler airplanes, a throttle block or starter block would probably be effective. So that's a second design approach to preventing an attempted takeoff with the controls locked.

Another design approach mentioned is to connect the gust lock with the nosewheel steering so the plane can only taxi in a circle with the control lock engaged. This one might be adaptable to RVs without too much difficulty.

Dave

As somebody who has a lot of Gulfstream time, including time in that very airplane, that crew did so many things wrong that it boggles the mind. I read the reports about how they operated and I just shake my head in disbelief.

i know the lawyer types look for deep pockets to blame, but there is NO excuse for taking off with a gust lock engaged. I have never flow any aircraft, including transport cat aircraft that did not have "controls free and correct" in a checklists somewhere. We had a crew do it in a RJ, they got lucky and got it back on the ground. they missed at least six things that should have stopped it. including the levers not being able to go past half way and only got about 56 percent thrust. "you cannot fix stupid, even with duct tape"

bob burns
N82RB

USE THAT CHECK-LIST!

At what point will we stop trying to make things idiot proof and take responsibility to do things right?

If you make it "idiot proof", someone will come up with a better idiot.

I always liked the control locks my old flight school has for their Diamond aircraft. It's an aluminum tube that hooks to the top of both the rudder pedals and runs up to the control stick. Two straps at the top of the tube run around the stick and are clipped under each corner of the instrument panel. The straps hold everything in place and prevent you from sitting in the seat while all control surfaces are secure.

the anti-splat gust lock is as close to idiot proof as you will get for an RV.

tales of idiots

I slid down in my seat one day... with the intent of moving the plane forward a hundred yards to the fuel pump. When I looked down at my anti splat gust lock... my reaction was to see if anyone was watching. Ego before all... I suppose.
No harm done as you can't move the pedals until it is removed. I hope not to repeat the mistake.

Controls free and correct. Every time, no exceptions.

"Pilot to copilot, hey did we remember to start the engine?"

rightrudder said:

Controls free and correct. Every time, no exceptions.

Click to expand...

In my checklist!

AndyRV7 said:

In my checklist!

Click to expand...

Excellent. Me too!

Mel said:

At what point will we stop trying to make things idiot proof and take responsibility to do things right?

If you make it "idiot proof", someone will come up with a better idiot.

Click to expand...

Exactly! And operation of aircraft is a "licensed" activity. That implies training, standards, skill, competence and consequences. No place for idiots.

Bevan

Let History not repeat itself!

What a concept -- a pilot's check list!
On October 30, 1935, at Wright Air Field in Dayton , Ohio , the U.S. Army Air Corps held a flight competition for airplane manufacturers vying to build its next-generation long-range bomber.
It wasn't supposed to be much of a competition. In early evaluations, the Boeing Corporation's gleaming aluminum-alloy Model 299 had trounced the designs of Martin and Douglas.
Boeing's plane could carry five times as many bombs as the Army had requested; it could fly faster than previous bombers, and almost twice as far.
A Seattle newspaperman who had glimpsed the plane called it the "flying fortress," and the name stuck. The flight "competition," according to the military historian Phillip Meilinger, was regarded as a mere formality.
The Army planned to order at least sixty-five of the aircraft. A small crowd of Army brass and manufacturing executives watched as the Model 299 test plane taxied onto the runway.
It was sleek and impressive, with a hundred-and-three-foot wingspan and four engines jutting out from the wings, rather than the usual two. The plane roared down the tarmac, lifted off smoothly and
climbed sharply to three hundred feet. Then it stalled, turned on one wing and crashed in a fiery explosion. Two of the five crew members died, including the pilot, Major Ployer P. Hill (thus Hill AFB , Ogden , UT ).
An investigation revealed that nothing mechanical had gone wrong.
The crash had been due to "pilot error," the report said. Substantially more complex than previous aircraft, the new plane required the pilot to attend to the four engines, a retractable landing gear,
new wing flaps, electric trim tabs that needed adjustment to maintain control at different airspeeds, and constant-speed propellers whose pitch had to be regulated with hydraulic controls, among other features.

While doing all this, Hill had forgotten to release a new locking mechanism on the elevator and rudder controls.

The Boeing model was deemed, as a newspaper put it, "too much airplane for one man to fly." The Army Air Corps declared Douglas's smaller design the winner. Boeing nearly went bankrupt.
Still, the Army purchased a few aircraft from Boeing as test planes, and some insiders remained convinced that the aircraft was flyable.
So a group of test pilots got together and considered what to do.
They could have required Model 299 pilots to undergo more training. But it was hard to imagine having more experience and expertise than Major Hill, who had been the U.S. Army Air Corps' Chief of Flight Testing.

Instead, they came up with an ingeniously simple approach: they created a pilot's checklist, with step-by-step checks for takeoff, flight, landing, and taxiing. Its mere existence indicated how far aeronautics had advanced.
In the early years of flight, getting an aircraft into the air might have been nerve-racking, but it was hardly complex. Using a checklist for takeoff would no more have occurred to a pilot than to a driver backing
a car out of the garage. But this new plane was too complicated to be left to the memory of any pilot, however expert.
With the checklist in hand, the pilots went on to fly the Model 299 a total of 18 million miles without one accident. The Army ultimately ordered almost thirteen thousand of the aircraft,
which it dubbed the B-17. And, because flying the behemoth was now possible, the Army gained a decisive air advantage in the Second World War which enabled its devastating bombing campaign across Nazi Germany.
Source: Wikipedia

...Thank you for this very interesting and informative bit of history. I am sure most people, myself included were unaware of the beginnings of the check list and it"s early use. Thanks again, Allan...

Often on the Biz jets I have worked on the auto throttle is an STC, i.e. a generic unit supplied by a third part. It is on the Challenger 600 series, so it would not have provision for an interface with the gust lock.

Where ever you draw the safety line, somebody will cross it and some lawyer will tell you after the fact that you should have drawn it in a different place. That's just life in this business.

I haven't even thought about gust locks on my 4 yet. But I guess I have a couple of yrs left to worry about it.

I lost many good friends going on a hunting trip in a Baron... control lock left in on takeoff everyone dead. very sad but true.

Back when I was in the C-170 Association, we had a fellow take off with the yoke tied back with the passenger seat belt. How do you overlook that?
But....... It happens.