Dow-Key Microwave switches on Boeing commercial airplanes

Citation

(2006), "Dow-Key Microwave switches on Boeing commercial airplanes", Aircraft Engineering and Aerospace Technology, Vol. 78 No. 6. https://doi.org/10.1108/aeat.2006.12778fab.012

Dow-Key Microwave switches on Boeing commercial airplanes

Dow-Key Microwave switches on Boeing commercial airplanes

Keywords: Aircaft components, Commercial aircraft

For roughly 20 years and counting, no commercial airplane has left Boeing Corp.'s manufacturing facilities without Dow-Key Microwave RF switches being outfitted within the aircraft manufacturer's collision avoidance and landing systems.

Chicago-based Boeing, specified Dow-Key in the late-1980s as the preferred supplier of RF switches for use in its Traffic Collision Avoidance Systems and Instrument Landing Systems. Today, Dow-Key provides its switches for all of Boeing's current fleet of commercial airplanes, including the 777, 767, 747, and 737, as well as the forthcoming state-of-the-art 787 Dreamliner.

When it is released for service in 2008, the mid-size 787 Dreamliner will be one of the most technologically advanced commercial airplane ever built.

A total of 43 top-tier supplier partners have provided state-of-the-art engineering, materials, and components in every area of the 787's design. New engines from General Electric and Rolls-Royce help provide unmatched fuel efficiency, nearly 20 per cent less fuel than similarly sized airplanes, and account for an 8 per cent overall efficiency in the entire airplane. The 787's one-piece fuselage eliminates the need for 1,500 aluminum sheets and 40,000-50,000 fasteners. Further, as much as 50 per cent of the 787's primary structure is made of advanced composite material, making the plane even lighter yet more durable. The 787's open-architecture design affords even greater efficiencies, including the possibility of using health-monitoring systems that gives the airplane the ability to self-monitor and report maintenance requirements directly to ground-based computer systems.

In flight, the 787 will carry up to 250 passengers and can travel at speeds up to Mach 0.85, similar to today's fastest wide-body jets, while its advanced safety systems ensure uncompromising passenger security from take-off to landing.

Like all of Boeing's commercial fleet of aircraft, the 787's Traffic Collision Avoidance System, or TCAS-II is equipped with Dow-Key's advanced RF switching technology for mission- critical performance.

The purpose of Boeing's TCAS-II, which is mandated by the Federal Aviation Administration (FAA), is to provide air traffic controllers with an aircraft's identification and altitude, while terminal radar provides relative position and distance. In operation, if the system detects a possible in-flight collision with another airplane, it presents to the pilot on the flight deck a series of advisories that tells the pilot to pull up, dive, turn right or left, and so on.

“Safety is of key importance for Boeing, and has strict requirements therein,” says Carl Abendroth, President of Kirkland, Wash-based Anzak Corp., an electronic components representative for Dow- Key. “Dow-Key provides Boeing with custom solutions to meet and surpass those safety requirements.”

Part of Boeing's TCAS-II employs the use of two antennas, one of the top of the fuselage and one below. Internally, these antennas are connected either to one of two Mode S transponders, which provide redundant support for a portion of the TCAS-II. In order to connect one or the other of the transponders to the two antennas, two Dow-Key 402-167 switches are used.

“While the FAA mandates the use of TCAS-II among all commercial airplanes,” explains Abendroth, “it allows for some options, one of which is a redundant Mode-S transponder. Not all aircraft manufacturers use a redundant system, but Boeing has done so for many years to ensure its customers solid reliability.”

Dow-Key, too, took a proactive approach years ago to assist airlines that already had Boeing planes in the field so that they could comply with the FAA mandate to add TCAS-II.

In 1987, says Abendroth, Dow-Key, with its innate knowledge of how its switches would best interface with the TCAS-II, assisted the airlines and maintenance organizations that used Boeing aircraft by offering engineering guidance – and in some cases even modifications to the Model 402-167 switches themselves – on how best to handle the retrofits in the quickest manner. Typically, retrofitting the TCAS systems into existing aircraft took airline crews about 1,000 man- hours per plane. Dow-Key helped all of them streamline these retrofits.

“After Dow-Key's diligent service to the airlines,” says Abendroth, “the company became Boeing's vendor of choice for the TCAS-II switch requirements.”

Equally important to ensuring safety in the air is an aircraft's ability to safely land. The Instrument Landing System, or ILS, in an airplane enables its pilots to acquire the specific RF signal that identifies their runway of choice. The ILS antenna acquires a glide scope signal, which can be described as an electronic highway with a decreasing angle that ends at the threshold of the runway. On all but the 787 Dreamliner, Dow-Key's Model 402-188-1 switches actuate Boeing's ILS equipment, allowing the flight crew to choose from a variety of modes in which to land as they get closer to their destination. Depending on the size of these other Boeing aircraft, the complexity of the ILS could require as few as two or three switches or as many as six or eight.

“The pilot can fly the glide path manually,” he continues, “or choose one of the various categories of auto- land, which typically is found as an ILS option on fully equipped airplanes that do a lot of international travel.” Auto- land mode, which includes auto-pilot and auto-throttle modes, is triggered by an extra actuation switch inside Dow- Key's 402-188-1 switch, when it acquires and is switched to that particular set-up antenna at the nose gear door.

“Here, too, as was the case with Dow- Key 402-167 switch for the TCAS-II, Dow-Key provided a level of customer service for the maintenance of its 402- 188-1 switch in an ILS that was unmatched by its competitors,” Abendroth states. Because of the higher quantity of switches that would be used on large airplanes such as the 777, Boeing customers wanted to be able to repair these devices in their own facilities should they require it.

“Dow-Key offered to provide them with a Certified Maintenance Manual (CMM) for the Model 402-188-1 switch,” says Abendroth. “Essentially, the CMM contains all of the proprietary information about this product: its parts, how it's built, adjusted, disassembled, repaired, reassembled, and certified to be able to go back on the airplane. This showed Boeing and the airlines Dow-Key's level of commitment to its products, and served to further strengthen the long- standing and successful relationship between Boeing and Dow-Key.”

Dow-Key also has been able to save Boeing much time during its qualification testing process for parts used on new airplane models, as per the Radio Technical Commission for Aeronautics document no. D0-160C.

“We have a lot of existing data on other programs that we have qualified,” explains Jovita Trujillo, Sales Operation Manager for Dow-Key. “We make it more cost-effective for Boeing by offering a qualification by similarity, which in turn drastically reduces the time and money that the company would have had to have spent on testing from the ground up. This can save them as much as a 50 per cent reduction in time specific to testing, which translates to a cost savings anywhere between 30 and 50 per cent.”

Trujillo adds that Boeing's internal quality and delivery ratings for Dow- Key's 402-167 and 402-188-1 switches are in the top 90s on the airplane maker's internal scale of 0-100.

“We monitor all of Boeing's orders on an internal weekly and external monthly basis to ensure that its deliveries are always on schedule,” she concludes. “From our perspective, it's not just about creating best-in-class switching technologies, but also being able to deliver solutions to our customers quickly and on time.”

Details available from: Dow-Key Microwave Corp., Tel: +1 850 650 2329, web site: www. dowkey.com