The torque link stop lugs are more important than you would think. Overextension of the nose strut due to a worn out stop lug can lead to a cascade of problems. McFarlane A&P mechanics have seen struts over extend to the point where the metering pin comes out of the orifice. This results in loss of damping action and the pin hammering the orifice every landing and distorting and enlarging it. Over time, the excess nose strut travel and lack of damping can result in fatigue cracks in the torque link arms. McFarlane recommends thoroughly inspecting all nose strut components when replacing a severely worn stop lug.

The stop lug also acts as a centering device aligning the nose wheel and wheel pant straight with the airplane and slip stream after it has left the runway. Worn stop lugs can allow the nose wheel to lock in a turned position in flight that will require holding rudder for coordinated flight. Retractable gear aircraft depend on the stop lug to properly center the nose gear steering before it retracts into the wheel well.

Strut seal leaks and flat struts can be caused by roll or twist of the main O-ring seal. It is very frustrating to carefully check all the parts and surfaces and put a new seal kit in the strut only to find it flat again after a relatively short time. We have seen this happen when a film of MIL-5606 hydraulic fluid dries out on the exposed chrome strut shaft. MIL-5606 by nature has a tendency to get sticky as it is exposed to air and dirt and then dry.

Very slight dried oil films are sometimes hard to detect and they can get past the plastic wiper seal. When this happens the sticky strut has a tendency to grab the O-ring and roll or twist it when the strut slides in or out causing the seal to distort. A very small O-ring twist or distortion will cause a leak. This phenomena is aggravated by the low pressure that the Cessna strut is designed for. Wipe the chrome strut down with Stoddard solvent (mineral spirits) periodically to soften and remove any dried oil film, dirt, dust and bugs.

There are many components all connected to keep the nose gear in line. If one component is worn or out of tolerance it can cause shimmy problem. Reference Dave McFarlane’s article: Can You Stop Nose Gear Shimmy instructions and suggestions.

Overlooked items also include the rod ends, shimmy dampener mounting and attachment, shimmy dampener, and steering collar. The steering collar is where the steering rod tubes connect and the upper torque link is attached to, along with the shimmy dampener on most aircraft. If the steering collar has play vertically and laterally and is allowed to tilt; that will cause excessive wear and force on the torque links, steering, and strut components. There are three different thicknesses of shims to help get the collar in place.

Ensure that the shimmy dampener is working properly with no dead spots in dampening action. The cylinder could be worn on the inside or on a piston that warrants replacement of components. All of the nose strut components are tied to each other and any movement is transmitted through to the tire and back through the dampening system, which if remedied will continue to be more pronounced.

It is very important to maintain proper torque for the bolts that clamp the chrome bushing/spacer at the upper attachments to the steering collar and the lower attachment to the nose gear strut. It is commonly thought that the chrome bushing/spacer is kept in position by the bolt filling the center bore of the bushing/spacer. This is not correct as the inner bore of the chrome bushing/spacer and the bolt are a loose non-precision fit. The bushing/spacer is secured by the bolt end, clamping the spacer so that it is tight between the arms of the aluminum forgings. Any looseness of this end clamp will allow movement of the chrome bushing/spacer. This movement will erode the aluminum forgings and create more free motion of the torque link.

All shimming of the torque links must be done with proper torque on the bolts. Periodically and during nose gear inspections, check the torque on the upper and lower torque link bolts. If the chrome bushing/spacer is allowed to move, the resultant wear can require replacement of the expensive aluminum forgings. McFarlane is working on a repair for the worn aluminum forgings. Unlike our competitors, extra care is given to the machining of the McFarlane chrome bushing/spacers to give the largest possible bearing surface to the ends that bear against the aluminum forgings. Chamfers or bevels are kept very small.

Our Vertical Fin Fitting kits include all the hardware needed for installation. You may receive NAS1149 hardware with the kit, which supersedes AN960 hardware (referenced in our ICA).

Flap Roller Kits contain all of the rollers needed to complete one aircraft. Flap Roller Upgrade Kits include all of the components, forward wear washers (P/N MCS1450-3S10-032), aft service kit (P/N MCSK100), and hardware needed to replace the flap rollers and hardware associated with the rollers, along with Cessna SEB95-3 Rev. 1 for instructions to inspect flap support arms for wear.

The screw kit depends on if the holes in the floor of your airplane have been carefully removed and are close to new size or if they have been enlarged by unskilled rivet removal or the rails have been changed before. It will make a difference if the previous rails installed were Cessna rails with predrilled holes in the rail. (They do not normally line up well and the floor has been mis-drilled some to force them to align). If the holes are good, use the SR6-SCREW-KT kit. If the holes are enlarged some, use the SR8-SCREW-KT kit.

It's just a matter of removing the doors, pressing out the steel bushings and then pressing in the replacement parts. The kits include all necessary hardware including new bolts and spacers. Where the OEM sleeve part is flanged, the space is made up with a thin washer. Installation videos are available to demonstrate kit installation. 

The kits fit exactly the same space that the OEM parts do. However, the most important difference is that the parts in the kits cannot corrode or seize together because of the self lubricating polymer bushings used to replace the steel bushings. If the steel OEM parts corrode and seize, the result is costly repairs to the supporting structure in the wing. 

Yes, one kit will do both the left and right main landing gear doors.

No, BMC kits do not caintain the piston. However, it comes with the hardware needed to complete the job and installaiton tooling.

Marsh Brothers developed a new poylmer formula specifically for aerospace which they call AeroTough™ GF, for "grease free". Lubricant is bult into the polymer, completely eliminating any need for periodic lubrication. 

The Cessna steering system is an engineering masterpiece that is simple in function while allowing good directional control throughout the transition from flight to ground or ground to flight, even in crosswind conditions. A key part of this system is the steering rods. The steering rods are a spring loaded device that applies spring pressure to pull on one side of the nose gear when it is activated and yet have a specified amount of free play in the opposite direction until a solid push is required for positive steering.

The following are some common symptoms of worn out or failed steering rods:

1. Weak steering (You can push on the rudder but not much happens and you have to use a lot of brake to steer. Often the weakness is one direction only.) The early Cessna steering rod springs were designed such that if the rudder pedal was pushed hard in one direction while the nose gear was pointed all the way the other direction and had some resistance to moving such as soft ground or snow, the spring could be compressed to an extent that it would be permanently shortened leaving it weak. McFarlane has redesigned the spring so this cannot happen.
2. More or less than 1.2 inches of free play movement or inconsistent free play of the steering rod shaft is present. The spring is retained by a washer that was stop swaged into the steering rod housing. During an overload, such as extra hard pedal force applied with the nose wheel pointed all the way in the opposite direction and restricted or undetected damage from a previous hard landing, the spring retaining washer can be deformed and forced past the swaged stop. This will result in inconsistent free play and erratic function of the steering rod shaft as the washer passes past its designed swaged stop in both directions. The rudder rigging in flight might also be inconsistent. This is a dangerous situation that results in inconsistent steering and the steering rod must be replaced. McFarlane has redesigned the washer and shaft machining to prevent the washer stop failure.
3. Rust and corrosion can make the steering rods unreliable. The steering rods get water and contaminates from the runway that the nose tire throws at them. The fit of the shaft into the bushing that is swaged into the housing is not a precision fit. This can allow internal contamination, moisture, and salt that will rust the springs and steel housing interior, leaving the components weak and subject to failure. Red rust streaking on the shaft exit area or bubbling of the exterior paint indicate corrosion failure. The McFarlane steering rods are made from 304 stainless steel and have a special corrosion preventative and lubricating coating on the springs to fight against corrosion and wear.
4. Wear of the shaft and bushing is caused by steering movement and aerodynamic pulse vibrations created by the rotating propeller. This wear can be detected as looseness of the shaft in the end bushing. Some wear is acceptable.

Yes, using a cooling shroud whether on a 200 series or 400 series dry air pump can reduce pump temperatures by as much as 10%. For more information, go to Vacuum Pump Cooling Kit.

The tool kit consists of a zinc-coated coupling spanner wrench and unique coupling gear socket with steel housing and aluminum gear engagement, designed to protect the steel coupling gear from damage during maintenance. Together, these tools allow the coupling to be held in place (mounted on the alternator or free-standing) while the coupling gear slippage is checked with a calibrated 3/8” torque wrench (as specified in the engine maintenance manual).

It is certified to meet AMS3320G, which is the same industry standard specification to which other fiberglass reinforced silicone baffle seal material is certified, however it is not an STC or FAA-PMA product. It is ultimately the installing mechanics responsibility to determine whether the material is appropriate to repair the baffle seals on a specific aircraft.

McFarlane does have FAA approved die cut baffle seal kits for the re-start Cessna 172 aircraft; please see P/N BSC-KT-1. We developed this first because our patented material solves the firewall crack and other baffle seal related problems on these airplanes. McFarlane will develop more FAA approved baffle seal kits as engineering time permits.

P/N MCSK100 Flap Roller Service Kit replaces the aft wide roller assembly, and only the aft wide roller. Please consult your applicable Service/Maintenance Manual and Illustrated Parts Catalog for the proper location for your specific aircraft, and the STC SA01074WI.