Yes, and multiple jets over the years WITH TRs have also run off the end of runways….

This whole debate over runway/airport conditions people would theoretically land or take off in based on having or not having TRs sure has a lot of similarities to the arguments being made against increasing the risk tolerances in with the Cirrus just because you have ‘chute…

Exactly.

The chute is a mission expanding piece of equipment. People fly to their level of risk tolerance, and they take risk credit with a chute, so they do more with the plane, but their risk profile is not actually less. Cirrus pilots on this forum have said this clearly such as "I won't fly at night without a chute". That's exactly trading risk credit of the chute for expanded mission capability.

The TRs expand the number of airports and conditions one can use with the plane. For a given risk threshold, the 525 fails to complete the missions, my V does complete the mission.

And it doesn't have to be actual risk, it can be potential future risk. On a day trip with a 30% chance of rain in the afternoon, do you fly the 525 to the remote airport? If it rains, you now can't takeoff until the rain stops and the runway becomes dry. So you don't go, and 70% of the time, it doesn't rain at all. Or you do go, and 30% of the time, your stuck for hours. Both are mission failures.

Meanwhile, the V is going and coming home, if it rains or not, and operating with no greater risk than the 525 on a dry runway. This is higher mission performance.

Mike C.

Your analysis is spot on, but that's to be expected. This is fundamentally an engineering question and you're an engineer.

It's the balance at the root of most engineering problems:

Pick 2:
weight/complexity, performance/capabilities, cost

What is the risk of TR deployment in flight?

I know it's rare, but does it ever happen?

Well yes, I think we have read about it in crash talk?

I do not think TR deployment in Flight has ever occurred on a citation

Exactly.

The chute is a mission expanding piece of equipment. People fly to their level of risk tolerance, and they take risk credit with a chute, so they do more with the plane, but their risk profile is not actually less. Cirrus pilots on this forum have said this clearly such as "I won't fly at night without a chute". That's exactly trading risk credit of the chute for expanded mission capability.

The TRs expand the number of airports and conditions one can use with the plane. For a given risk threshold, the 525 fails to complete the missions, my V does complete the mission.

And it doesn't have to be actual risk, it can be potential future risk. On a day trip with a 30% chance of rain in the afternoon, do you fly the 525 to the remote airport? If it rains, you now can't takeoff until the rain stops and the runway becomes dry. So you don't go, and 70% of the time, it doesn't rain at all. Or you do go, and 30% of the time, your stuck for hours. Both are mission failures.

Meanwhile, the V is going and coming home, if it rains or not, and operating with no greater risk than the 525 on a dry runway. This is higher mission performance.

Mike C.

Extremely low.

As far as I know, inadvertent TR deployment in flight is suspected (not proven) in only one Citation accident:

https://aviation-safety.net/database/re ... 20160816-0

I can't say I am sure this was TR related, but it could have been. The video is too crappy to visually see it, but the flight path would be consistent, but other causes are possible, such as yaw damper hard over. Lack of better video and lack of a proper crash investigation leave questions unresolved. It is possible the pilot did not know or do the emergency stow procedure which would have resolved this issue and prevented the accident.

The TR design has locks to keep the buckets in. The squat switches prevent you from unlocking the buckets, and there are pins in the reverser levers to prevent their activation as well.

Should the bucket come out, it will yank the throttle on that engine to idle thrust through a dedicated linkage.

There are emergency stow switches on the panel which will force the buckets closed. These are tested on every takeoff. You can see them to each side of the caution panel and fire lights here:

In flight TR deployment is practiced in the sim. It is not particularly violent. The procedures are pretty simple, hit the emergency stow, slow down to specific speeds, let them stow or deal with them out until landing.

It had been demonstrated during certification that you can land with a bucket deployed if all the above safety and procedures don't work.

In flight TR deployment is way, way down on my list of things I worry about.

Mike C.

Of course.

The TR is a piece of equipment that improves the capability of the airplane. You can use that capability to expand the missions you can do safely.

This is no different than having a STOL capable airplane and landing on shorter runways. The airplane equipment opens up more use cases.


Because the manual gives me the data for that operation.

While the charts for dry runways do not give credit for TRs, the charts for contaminated runways do give credit, at least mine do.

Here is an example for the Encore (nicer formatted table than mine):

If there is a chart in the manual showing numbers for use of the TRs, then that indicates the probability of deploying the TRs is high enough to rely on it.

Mike C.

There was one accident where they tried to go around (from a bounce, I think) after the thrust reversers were deployed, contrary to the AFM. The mousetraps activated resulting in loss of thrust. The mousetraps were removed.

Textron is not updating the G1000 software, the STC locks in a particular SW rev. Why it did that is unknown, might have been simply that they specified the SW rev in the paperwork and thus this limitation was somewhat accidental.

On my GTN + TXi system, I've already had 2 SW updates that added features. The STC is not limited to one particular SW rev and I get to ride the improvement curve with everyone else having similar equipment.

I don't need Textron to support some particular frozen in time set of equipment since my stuff is the same as the general market and Garmin supports that directly.


On my upgrade, I saved 380 lbs (and this was actual pre and post weighing, not just W&B math), so I think your comment about weight savings isn't correct, the weight savings are substantial for a GTN + TXi upgrade, and may be more than the G1000 even.

Yes, 380 lbs. Half of it was wiring and trays that were removed. The prior owner complained the plane was nose heavy and they had to force people to sit towards the rear and put ballast in the tail when they had a number of passengers. Now I have the opposite problem, ballast when I fly solo, but this goes away as the passenger count increases, which is a far better situation. Being near the rear CG limit also makes the plane faster and climb better.

My weight savings was with keeping the SPZ 500 autopilot system. If I could get a GFC 600 (which is possible for a CJ, there is an STC), then I could remove 13 other boxes in my airplane saving another 100+ lbs of weight. This includes removing all of the AC inverter system since the only AC equipment on the airplane is the SPZ 500 presently.

Mike C.

I managed a G1000 CJ and currently manage / fly a CJ with the G600TXI and 750s w/ GFC 600. Both are a joy to fly.

The issue with either upgrade is the amount of ballast we have to carry up front when we fly SP or no pax up front. The G1000 was around 200lbs, the G600TXI is about 150lbs.

Still, I'd choose a G600TXI CJ over a CJ1 as the avionics are newer, cheaper to repair, and more reliable in my experience.

-Citation Jet Exchange

Flying with ballast up front is far superior to having to ballast in the back as the previous owner had to do with my plane.

For my plane, me flying solo, 200 lbs in the nose. Flying 2 up front, 50 lbs. Flying 3 or more, no ballast.

I carry some tools and spares which add up to around 100 lbs, so I only need 100 lbs when flying solo, and no ballast when flying with anyone else. Putting luggage up in the nose reduces the ballast requirements.

My ballast system is landscape rocks in plastic bins. A 0.5 cu ft bag of landscape rocks at a home store is $4 and weighs 50 lbs. Example:

https://www.homedepot.com/p/Vigoro-0-5- ... /100558618

It is more compact than water ballast and does not freeze or leak. It is vastly cheaper than purpose made ballast bags with lead or steel shot. If I am away from home and need ballast, I can buy it at a home store for $8 per 100 lbs. If I am away from home and need to drop the ballast, just empty the rocks out of the bin anywhere gravel is by the side of the road. In most cases, I know before leaving home base whether I need the ballast or not, so simply load it or not in the hangar. I have so far never had to dump or buy ballast away from home base. I generally fly with the ballast on the plane since I rarely need max useful load.

I intend to move my oxygen cylinder from the far rear to the nose which will reduce these numbers by about 50 lbs. This is a shift of over 30 feet in moment.

If fooling with ballast is annoying to you, you can have lead plates permanently installed in the far forward nose. This is about 23 ft forward of the CG in my plane, so it doesn't take much. You are still significantly lighter than before the mod.

Mike C.

But that's the mission. And yes, if you're flying to the cabin for a weekend or to go skiing, deviate all you want.

This is a package delivery service and the package is surgeons who will operate on people who otherwise would have to drive 6 hours over snowy roads. It's a very reasonable mission.