Regional Jet Landing Gear Systems

After many years as a passenger and a considerable number of jump seat trips, I can truly say that my most enjoyable part of the flight is when the landing gears are either in the “down and locked” or the “up and locked” positions. I love the sight of three green lights and the sound of landing gears doing precisely what they are supposed to do. I have also noticed that landing gears don’t get much press until they don’t do exactly what they are supposed to.

Modern landing gear systems exemplify the concept of aircraft quality and those on regional jets flying short haul flights are probably the gold standard for reliability. These gears are in service for eight to 10 years and go through 10,000 to 15,000 cycles before coming in for overhaul. I find it amazing that all those links, actuators, and the strut perform as designed, and without fail, even during winter operations. I thought that it would be interesting to discuss this mystery with some experts in servicing aircraft landing gears and in cold winters.

Aviation Representatives Inc. (Av-Reps) is a Canadian company specializing in component repair and overhaul for regional and larger commercial aircraft. It began operations in 2000 and has grown to occupy a 27,000-square-foot complex located in Mississauga, Ontario near Pearson International Airport (YYZ). It is certified to maintain and supply components by Transport Canada, EASA, Bombardier and is FAA accepted through the U.S. and Canada bilateral agreement.

In the regional markets it supports the Canadair CRJ 100/200, CRJ 700/900, Bombardier DHC-8, ATR 42/72, and Challenger CL601/CL604. Its expertise is exchange, repair, and overhaul for DHC-8, Q400, ATR, and CRJ series aircraft landing gear systems. These include the main and nose assemblies, drag struts, yoke assemblies, stab stay, and steering components. The majority of AV-Reps’ business is from repeat customers and referrals. It has a reputation for quality service and employing top-notch technicians that save its customers money.

Technical staff

Av-Reps has about 35 experienced, well-trained maintenance technicians that were recruited from the military, automotive industry, airlines, and local machine shops. Av-Reps’ in-house technical training programs are recognized by Transport Canada, EASA, FAA, and the Canadian Council for Aviation & Aerospace (CCAA). The CCAA is a Canadian not-for-profit organization that helps business, labor, educators, industry associations, and government agencies address the critical human resource needs for the industry.

During an interview, Robert Takacs, vice president sales and marketing, and Paul Redkin, quality manager, commented that Transport Canada was currently in the shop conducting an audit of its training and quality programs.

I asked about EASA audits and they said, “Transport Canada auditors were dual qualified and were conducting EASA audits concurrently.” Redkin mentions that they always receive high marks from the auditors for their quality and training programs.

I asked Av-Reps if their landing gear and component overhaul business came from any particular segment of our industry or geographical location. Takacs says that they receive work from customers as far away as New Guinea and as close as next door at Pearson International. Landing gear and components are overhauled for large commercial carriers and regionals, at about a “40 to 60 percent ratio.”

The company doesn’t specialize in a certain fleet type but being located in Canada, it does a lot of Canadair CRJ 100/200, CRJ 700/900 and is beginning to get a significant amount of Q400 work. Having overhauled more than 100 sets of nose and main landing gears for the DHC-8 establishes Av-Reps as a bit of an expert for MRO on these landing gear.

Landing gear maintenance schedules

Regional operators have a variety of landing gear maintenance programs. Av-Reps works with its customers and tries to develop an annual paired removal schedule. It also has an exchange and Aircraft On the Ground (AOG) program, and when needed can get a fresh gear out to the customer quickly.

When asked about some of the common problems they see in overhaul, Redkin says, “Corrosion is our nemesis and it is problematic for aircraft that fly Caribbean or Pacific routes. Corrosion is often found under bushings and on gland nuts and mating threads and is caused by salt, moisture, and dissimilar metals.”

According to Av-Reps, “Modern aircraft landing gears are extremely durable and can make about 10-15,000 cycles before they are removed and overhauled.” Redkin says that “only about 5 percent of customer gear removals are unscheduled. These are usually caused by corrosion, fluid leaks, or cracks. There can be a considerable difference in time and cost between the two scenarios. In unscheduled removals we don’t dissemble the gear. We follow the manufacturer’s troubleshooting practices until we locate the problem, then stop and implement a repair or component replacement and return the gear to service. Time is money for the regionals and we want to get their gears returned to operating spec and out of the shop as quickly as possible.”

Overhaul processes

I asked if there was one specific landing gear component that was more problematic than another. Redkin says, “We do not see a trend in gear or component wear or malfunction. No one component stands out.” This certainly speaks to the reliability and durability of modern landing gears.

I asked if they had a brand name quality program like Lean Production or Six Sigma. Redkin says, “We do not have a brand name continuous improvement program. We developed our own quality system that is an inspection intense work process supported by a custom software package. As you review our workflow process you will notice that a component is checked many times during our overhaul process. Depending on the gear and bill of work, the total turnaround time for overhaul can range from 25 to 45 days.”

The production team involved in an overhaul includes technicians, production managers, director of maintenance, and QA inspectors. The outcome of these stage inspections is almost nonexistent warranty work, “less than 1 percent,” and “very reliable gears.”

For example, Takacs informed me, “Some of our technicians get to see DCH-8 gears that we previously overhauled and have made another 10,000 cycles. Again, most of our business is repeat customers and new ones are from referrals. Our goal is to develop long-term relationships with our customers so we strive to deliver a flawless level of service and reliable components. We also get compliments and high marks for our quality program from Transport Canada auditors.”

Av-Reps’ quality program and work process benefit their customers in several ways. It considers Transport Canada a partner and they work together to find practical solutions that benefit operators. According to Redkin, “Because of our relationship with Transport Canada we have been able to design several cost-saving repair schemes.”

In Canada, you can follow manufacturer’s specifications or present your arguments for a concession to the Transport Canada Design Approval Organization. In some cases they have been able to get these concessions for their authorized repairs without going through lengthy approval from the manufacturer. Occasionally, they can save their customers about half the cost of the traditional repair. This is extremely important when considering that a new nose gear for a DCH-8, 100 series is around $187,000 USD and a main gear is around $296,000 USD. The nose gear for a Q 400 is about $1.2 million USD and the main gear is $998,000 USD. In one instance, “Av-Reps was able to get Transport Canada approval to ream a steering manifold body on a DCH-8 and save the customer about $6,000 USD.”

I asked if Av-Reps could offer any tips or advice to help operators extend the service lives of landing gears and reduce overhaul costs. The company suggested several practices that could save time and money. “Keep the oleo strut serviced, follow the work cards, and keep all the gear links lubricated; this makes a significant difference in the overhaul bill of work. Inspect the gear bushing and gland nuts to ensure that the protective sealant is intact. Keep all chrome surfaces on struts and actuators clean and inspect for FOD damage.”

After the interview with Av-Reps it appears there is no big mystery about aircraft landing gear systems. The explanation is practical aeronautical engineering, quality materials, modern manufacturing processes, and maintenance. As AMTs we should strive to be as reliable as these landing gears and follow those work cards. We know it’s all about preventative maintenance! AMT

 

For more information visit www.av-reps.com.

Charles Chandler began his aviation career as a junior mechanic for American Airlines and retired after 27 years of service.

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