Runaway Trim?

[Beantown]

I was wondering if anyone had heard about a CHQ ERJ that had to declare an emergency Thursday night coming out of BOS heading for ROC due to a possible runaway trim problem?

I had a friend that was on the flight. He is a private/inst pilot (but not a professional pilot). He said that the takeoff and first few minutes were normal. Then about 5 to 7 minutes in to the climb the nose started to pitch up beyond what he felt was a normal climb attitude. Soon he heard numerous bell's and whistles coming from the flight deck. He then started to feel the plane buffeting from the imminent stall. This lasted for a few seconds and he then saw the flaps go down a notch and it seemed that the crew was starting to get control (at least a little bit) of the plane. Soon after the flight attendant told the pax that they were returning to Boston and starting going over how to survive a crash landing. At this point the pax were in full panic and calling there love ones and saying there goodbyes. He said that it felt like the pilots were struggling to keep the plane in the air and that they were not at normal flying speed. The crew was able to get the plane on the ground and to my knowledge no one was hurt. (Kudos to the crew and the flight attendant). My friend was so shook up by the experience that he rented a car and drove back to Rochester. (He is an experienced pilot that owns his own small plane, so that shows you how rattled he was).

Does anyone know what actually happened with this plane?
I have heard that this kind of thing has happened before on the ERJ, true? If this is true, are ERJ crews trained on how to handle this situation in the sim? What do ya think? -Beantown

 

[chperplt]

Don't know about the flight, but you write a good story... ever think about writing books???

 

[skydiverdriver]

So, the pilots let it get close to a stall, without simply pushing that little button that turns off the autopilot? This doesn't sound plausable to me, but I have been wrong before.

 

[InHot]

Autopilot/Stab Trim

Bubba,

You know better. Runaway stab trim isn't necessarily associated with the autopilot. Don't know about the ERJ, but every jet I've flown had a stab trim switch you can use to disconnect the trim.

Maybe, it didn't work, who knows.

In any event I've learned never to armchair QB.

 

[atk]

On this particular flight the pitch trim from what I understand went to the full up position. This has been a problem with the EMB, the NTSB and FAA are investigating. The crew did a great job maintaining control of the A/C!! From what I understand "pushing the little red button" didn't help!!!!!!

 

[DorkProp]

Okay, this isn't really related to this thread, but not worthy of starting a new one.

In line for takeoff at CVG yesterday with 30-40 knot gusts, we were number 274 for takeoff (only slightly exaggerated). In front of us were boeings, douglases, a BAC jet, several CRJs, ERJs, and a DorkJet. The wind was directly from behind. All the aircraft's elevators were rigid and deflected down and seemed to not be affected by the strong wind. However, all of the ERJ's elevators were literally "flopping" nearly full-scale up and down at a rapid pace. Is there a flaw in the design of their gust lock? That just looked really bad for the elevators and control mechanisms.

Just wondering, not that this has anything at all to do with runaway trim.

 

[EagleRJ]

The gust lock is a problem on the ERJ, however it is not related to the pitch trim problems. The gust lock is a mechanical lock in the cockpit, and when you figure in over 100' of control cable, the elevator really takes a beating when the wind is blowing. Embraer and the companies that fly the plane have been aware of the issue and are working on a solution.

The pitch trim problem stems from the fact that there are two pitch trim servos- a primary and a standby. They operate independantly, and when the tail is highly loaded, it's possible for the servo to become stalled and unable to move the tail. This happened for the first time to an Eagle crew in Chicago, and they did a heck of a job getting the plane back on the ground. As far as I know, Embraer is working on that problem too, maybe by reworking the trim system so that both servos work together.

 

[Beantown]

<<<As far as I know, Embraer is working on that problem too, maybe by reworking the trim system so that both servos work together.>>>

They may want to hurry up and rework the problem before many get killed!!! -Beantown

 

[stingray]

"Know where your breakers are", if you can't disconnect the trim pop the breaker

 

[EagleRJ]

"Know where your breakers are", if you can't disconnect the trim pop the breaker

That wouldn't help. This isn't a runaway trim issue- the trim servo is stalling and is unable to turn the jackscrew. Running the procedure for a runaway trim just gets you into more trouble, because the checklist tells you to disable the primary trim servo and use the standby, which will reduce your chances of retrimming the aircraft.