Common Flight Simulator Failures

Problems frequently experienced by flight simulator operators

This article strictly applies to what we call basic and advanced flight simulators, Level C and D Full Flight Simulators are generally highly engineered machines costing multiple millions of dollars and should not suffer these problems1.

This articled is only intended to discusses common problems which arise after simulators are installed at the operator's facility and doesn't cover design flaws or uncommon problems.

* NexGen Simulation offers extensive repair, refurbishment and recertification services for third party simulators of any make or model *

Cosmetic Problems

Many people think cosmetic problems are unimportant, however a simulator with poor appearance will set up poor expectations and a bad attitude in users. Negative emotions regarding the learning context are widely agreed to be detrimental to absorption and retention of material.

Cockpit labels rub or peel off

Generally this is because inappropriate decals were used where silk screening, or other abrasion resistant techniques would have been more durable. It can also be that inappropriate silk screening ink was used. All NexGen silk screening and decals are designed to hold up for the life of the simulator (generally 20,000 hours of use or 10 years). What happens if they don't? Simple, we fix it.

Upholstery wears though

Many simulators feature commercial office carpets, and fabrics designed for residential chairs. It's important that automotive grade materials be used to prevent wear through, and edges properly finished to prevent fraying. Even then the selection of a correct material is important as most cars are not designed for use thirty to fifty hours a week. If lower grade materials are used a busy simulator might need to be reupholstered after just one year. A busy flight simulator can see as much use in one year as a car does driving 150,000 miles (241 402km)2.

We recognize that proper upholstery can be quite expensive and if a simulator is to see less vigorous use it may be more cost effective to use less durable materials. This is a decision that has to be made with the customer's price point in mind.

Paint wears off

It's paint, that's what it does when it's touched repeatedly. Powder coat should be used whenever possible on any surface which will be touched. Typically the first place to go is where do you grab the simulator to get in and out. Once that wears through all bets are off, the chipping slowly spreads as the panels under it flex and break the bonds. If paint must be used it's important that automotive grade paints used and properly applied. We prefer the powered coat and then vinyl wrap our simulators. The powder coat provides excellent protection and the vinyl allows users to brand their simulators and protects the powder coat. When the vinyl wears through replacement is quick and easy. We can provide multiple replacement panels for the common touch points so that operators can refresh the high wear points as needed.

Mechanical Problems

Chassis squeaks and wobbles

This is a common problem if the chassis is bolted together instead of welded. Even if the simulator doesn't move, the users do. Over time bolted together assemblies can become loose, particularly if they're not designed properly, and correct fasteners aren't used. This is also a problem when plastic or composite panels are mounted improperly. Frequently we see thermoplastic panels mounted directly to extruded channel frames. Since the frames are not rigid over time the flex causes the screws to chew ever larger holes into the plastic and eventually the panels rattle or pop loose.

Latches and closures no longer fit flush or don't close properly

If the simulator has recently been moved: This is usually because it's no longer sitting in the same position it was before, for example it may be on a slight hump in the floor, or on a floor which isn't level. This shouldn't happen, in an ideal world the simulator would be rigid enough to overcome this problem, however many are not. This can be an issue which is a difficult to correct. Simply shims may provide some relief however because the occupants of simulators tend to move quite a bit and jostle the chassis getting in and out the shims tend to work loose after a while. Leveling the floor or building a permanent fixture to correct the problem is a better solution.

If the simulator has not been moved: Again this is a generally problem arising from limited manufacturing capabilities. Many simulator companies do not have in-house welding welding facilities and will resort to bolting together structural components. Those bolts come loose over time and the frame flexes. Generally this can be fixed by shimming the frame into the right position and then tightening the bolts. Sometimes this is a result of a badly designed frame which warps or sags. This can usually be fixed but requires some more work. We do offer repair services for third party simulators.

Electrical Problems

Indicator lights burn out, or lose color

The bulbs were designed for continuous usage, or a lower voltage were used. Bulbs designed for continuous use generally don't like to be turned on and off and wear out quickly. NexGen prefers to use LEDs rated for 20,000+ hours when possible. However for regulatory reasons on some simulators the indicator lights must exactly match the aircraft and if the aircraft doesn't have LEDs we can't use them. In that case it may be possible to use bulbs which are designed for a higher voltage and run them at a lower voltage increasing longevity, provided that the regulatory requirements are met.

Switches fail

This is another case of selecting the wrong components. Most switches are not designed to be flipped dozens of times a day. It's nice to have switch gear that matches the aircraft exactly and often manufacturers will choose switches which aren't as durable simply because they look right. For an uncommonly used switch this is usually fine as most can handle thousands of cycles. For a commonly used switch though it can be an issue. If correct high-cycle switches are not available they will need to be manufactured in order to ensure longevity.

Controls lag or no longer provide fine grained input

This only applies to simulators that didn't lag when they were new and which haven't experienced any hardware or software changes. This is usually a problem with electrical noise on the analog channels which are measured by the control input boards. This can occur when sensors become loose or wear out. The solution in these cases is simply to check all of the electrical connections and re-tighten anything that is loose. Worn out sensors should be replaced. In an ideal world only non-contact sensors would be used however sometimes that's simply not practical and a properly designed system which uses more traditional sensors can still last many years. For major components NexGen always prefers to use non-contact components such as hall effect position sensors and rotary optical encoders.

Software Problems

These days most of the software systems for simulators are quite reliable in that they don't crash or do unexpected things during operations. However there are some concerns.

Simulator bogs down during normal operations

The number one cause of this is an insufficiently powerful computer running the visuals. The second most common is an auxillary process consuming resources

Manufacturers will sometimes test their hardware configurations at a specific airport with specific scenery and then when the customer requests custom scenery it may exceed the limits of what the computer can gracefully handle.

This can be a big problem for operators of simulators which have regulatory approval as a fixed device (vs an "as installed" or "site" approval). In the case of fixed approvals altering the device or it's configuration will void the approval. The only solution other than flying a different scenery location is to upgrade the graphics hardware or turn down the graphics settings and have the device re-approved. NexGen offers flight simulator upgrade and re-approval services for most third party simulators.

Another problem is that many manufacturers now require the simulator to be connected to the Internet to verify the software licenses and provide remote technical support. Of course being connected to the internet means the machine should have anti-virus software installed. If the simulator begins a scan mid-flight then the simulator will generally bog down unacceptable. The solution is to simply schedule the scans to only happen during times when the simulator isn't in use.

Scenery blinks in and out of existence

Do you have trees and buildings that just vanish can come back? This is usually the result of the visual engine detecting a glut of polygons in the scenery and culling them to maintain the frame rate. The same advice as for the bogging down section applies.

  1. They also generally have service and maintenance agreements which cover most of these problems. NexGen Simulation also offers service and maintenance agreements for our simulators. 

  2. That's assuming a busy flight simulator 12 hours per day, 6 days per week, 50 weeks per year; and any car driving that much is doing highway transport and averaging 45 miles (72km) per hour. In reality many simulators are booked 24 hours a day 7 days a week with the only down time being for service and major holidays.