What do you get when two world-class companies team up to make a great product even better? You get the MD Helicopter’s Explorer helicopter with an all new avionics suite from Universal Avionics Systems Corporation. You might call it the “Arizona Connection,” with MD Helicopters located in Mesa, AZ, and Universal Avionics located about two hours down the road in Tucson, AZ.
A Little History
MD Helicopters traces its roots back more than 50 years to when the Hughes Tool Company Aircraft Division first started to develop “light helicopters” in 1955. After years of successfully manufacturing such models as the Hughes 269, 300, 500 and 530F for civil use, and the TH-55 Osage, OH-6 Cayuse and highly-successful AH 64-Apache, Hughes sold its helicopters business to McDonnell Douglas in 1984. For the most part, McDonnell Douglas stayed true to the original Hughes designs and nomenclatures.
In 1997, McDonnell Douglas merged with Boeing to become the Boeing Company. In 1999, Boeing sold the former MD commercial helicopter lines to MD Helicopter Holdings Inc., an indirect subsidiary of the Dutch company RDM Holding Inc. Included in the sale were the MD 500E and MD 530F single-engine helicopters with conventional tail rotors. Also included in the sale were the MD 520N and MD 600N single-engine helicopters with the Boeing exclusive NOTAR no tail rotor system for anti-torque and directional control, and the MD Explorer series of twin-engine, eight-place helicopters.
Boeing maintained the AH-64 line of helicopters and rights to the NOTAR system.
MD Helicopters Holdings Inc. was acquired in July 2005 by investment fund Patriarch Partners LLC. The company was recapitalized as an independent company, MD Helicopters Inc.
MD Helicopters’ current product line includes the MD 500E, MD 530F, MD 520N, MD 600N and the MD Explorer.
MD Helicopters chose to differentiate itself from other
helicopter manufacturers with its use of NOTAR technology. Using the natural characteristics of helicopter aerodynamics, the NOTAR anti-torque system provides safe, quiet, responsive, FOD-resistant directional control. The enclosed variable-pitch composite blade fan produces a low pressure, high volume of ambient air to pressurize the composite tailboom.
The air is expelled through two slots which run the length of the tailboom on the starboard (right) side, causing a boundary-layer control called the “Coanda effect.” The result is that the tailboom becomes a “wing” flying in the downwash of the rotor system, producing up to 60 percent of the anti-torque required in a hover. The balance of the directional control is accomplished by a rotating direct jet thruster.
In forward flight, the vertical stabilizers provide the majority of the anti-torque; however, directional control remains a function of the direct jet thruster.
The NOTAR system eliminates all of the mechanical disadvantages of a tail rotor, including long drive shafts, hanger bearings, intermediate gearboxes and 90-degree gearboxes.
Universal Avionics Systems Corporation
Hubert L. Naimer, known for his innovative ideas for the modernization of cockpit flight instrumentation, founded Universal Avionics Systems Corporation in 1981. As early as 1976, Naimer had a vision of a master navigation system that would compute the input of a variety of sensors on an aircraft and provide guidance throughout all phases of flight. With his personal conception and vision, Naimer introduced the first flight management system (FMS) to the corporate aircraft market in 1982. Since that time, Universal Avionics’ vision has expanded to include product development of advanced avionics systems for the entire flight deck.
An international helicopter industry advisory board guided the design and development of the MD Explorer with an objective to produce a multipurpose twin-engine helicopter that would set new standards in performance, affordability, dependability and safety.
The MD Explorer was initially certified under FAA Part 27 in December 1994, and is currently certified by FAA and JAA for day/night VFR and single pilot IFR with full Category A design standards to JAR-OPS 3 Performance Class I.
Powered by two Pratt and Whitney Canada PW207E engines, the MD Explorer features a fully-articulated main rotor system, bearingless composite flexbeams and rotor hub. Anti-torque control is provided by the patented NOTAR system that reduces pilot workload and external noise levels, and improves safety significantly in confined areas and on offshore platforms.
The six-place MD Explorer cabin is the largest in the light twin class and is accessed through two 52-inch (1.32m) sliding cabin doors and a large baggage compartment. The large cabin makes the MD Explorer well suited for rapid role change from an offshore/onshore six-place passenger transport, to emergency medical services or law enforcement missions.
MD issued a request for proposal (RFP) in mid-2011 for a new avionics suite for their MD Explorer helicopter. It received interest or responses from numerous avionics suppliers. A first round of proposal reviews narrowed the field to two suppliers. Those two were invited back to MD Helicopters for discussions on the technical and commercial merits of their proposals. After further review of the proposals, MD Helicopters selected Universal Avionics as the supplier for the next generation avionics suite on the MD Explorer type aircraft. The entire process took approximately six months to complete.
The Universal Avionics system provided the best fit for the MD Explorer aircraft. It provides a high degree of capability and performance and enables ample growth for future improvements.
Specifically tailored for the low altitude operations of rotorcraft, the new flight deck features display graphics that are video and mission display capable.
The primary flight display (PFD) provides all primary flight parameters, primary engine/rotor data and safety critical annunciators, while the multi-function display/engine indicating and crew alerting system (MFD/EICAS) replaces the current IIDS and radar displays with synoptic displays. Synthetic vision, enhanced moving maps, system displays, electronic charts, checklists and innovative user interfaces are part of the baseline. Cockpit configurations, including single- and dual-pilot arrangements, are supported.
While reducing pilot workload, the new avionics suite will be available for forward fit and retrofit installations on the MD Explorer. The new avionics suite will enhance the aircraft’s performance by reducing the aircraft’s total weight by almost 30 pounds, providing enhanced situational awareness and functional growth capabilities. The consolidation and integration of currently federated functions also improves cockpit resource management (CRM).
The new avionics suite replaces the following federated displays:
• The existing EFIS 40/50 EADI, EHSI, control panels and remote symbol generators
• Existing integrated instrument display system (IIDS) for engine and annunciator displays
• Existing KAV-485 altimeter/VSI display
• Existing secondary CDI displays
• Existing airspeed indicators
• Existing radar/MFD displays
• Existing mechanical stab trim indicators
• Existing supplemental fuel quantity indicator
• Most existing panel mounted annunciators
• Standby altimeter and standby attitude display replaced by new integrated standby unit
The new avionics suite adds the following displays:
• Two or three 10.4-inch diagonal eight-by-six-inch landscape format Universal EFIS displays
• One EFIS control display unit
• One SD card server unit
• One speed/heading/ASEL select control panel
• One EFIS data concentrator unit (DCU)
• Two engine data acquisition/CAS units (DAU)
• One HUMS computer
• One integrated standby display unit
The displays have been further optimized for rotorcraft use in that they meet helicopter environmental requirements and will have an option for night vision instrument system (NVIS) lighting.
Display formats are designed to present both primary engine data (Torque, EGT, and NP-NR-NP) as well as all attitude, heading and air data information on the PFDs. The vertical speed and radio altitude information has been enlarged for improved readability. Drift vector and velocity data is shown for hover operations. Secondary engine data is presented on the MFD/EICAS display. A unique point-and-click interface for display control is mounted on the cyclic-mounted slew switch.
The avionics suite is offered in a baseline configuration for the pilot of PFD and MFD/EICAS displays. A PFD for the copilot is optional. The avionics suite includes a dual Archangel air data attitude heading reference system (ADAHRS), and dual Garmin GTN-650 GPS with GTX-33 transponder. The avionics suite will also accept other sensor digital inputs and can convert analog inputs through the data acquisition units (DAUs).
Since the avionics suite will be incorporated into the MD Explorer type design, there is no STC package. All forward fit installations will be done at the MD Helicopter factory. Retrofit options for aircraft already in the field will be made available, and MD Helicopters will most likely support these as factory retrofits. There is a possibility that MD Helicopters may eventually offer the retrofit at select service centers, but that decision has not been made as of this writing. All MD Explorer aircraft sold between now and the type design approval of the Universal Avionics system will be sold with a retrofit upgrade.
From an installation perspective, there is considerable alteration of the instrument panel to accommodate the new avionics suite. Aside from the physically larger displays, there is a change in location for other LRUs. Additionally, electrical system and wiring modifications are required to support the integration of the avionics suite into the current airframe. As with most new avionics systems, multiple digital buses are used to reduce the size of wire bundles. These include:
• A high-speed network bus between displays and controllers
• ARINC 429 data from the ADAHRS and AFCS
• RS-422 data from the DAUs to the displays
• Digital serial data from other LRUs
The avionics suite employs extensive built-in-test (BIT) and some user-activated test functions to help determine if the system is operational. There is also an Ethernet interface to a Web-based browser for initial setup and diagnostics. The Ethernet interface is also utilized to accomplish any LRU programming that is required.
Maintenance is pretty straightforward. All of the avionics are on condition only, so no scheduled maintenance is required. That means that if it is working, leave it alone. There are no 100-hour, 300-hour or any hourly inspections required. As with all glass displays, a lens cloth similar to those for cleaning glasses you might wear and isopropyl alcohol is a good combination. Nothing abrasive such as paper towels should be used on the glass. Harsh solvents and petroleum-based products should never be used to clean the displays. The displays incorporate a filter stack that includes anti-reflective filters to eliminate glare. None of these filters need to be removed, cleaned or checked on any kind of schedule.
Heat dissipation is always a challenge for displays and these units use a combination of cold wall convective cooling and integral fans.
To determine if the system is operating as it should, the BIT, power on self-tests, and user-activated testing to see if any faults have been logged. There are also no color calibration tests that can be done in the field.
About the only routine maintenance to be done on the system is the cleaning of the displays and the controller keypad. On removing and replacing any LRU, follow the instructions in the instructions for continued airworthiness (ICA). If an LRU is removed and replaced, the return-to-service procedure was accomplished by an automated test at the repair station. Once installed in the aircraft, the LRU should also pass the power on self-test.
Lastly but not least, some common sense should be used when working on this system. As avionics systems become more miniaturized, they become far more susceptible to handling and power issues. A few good rules to follow are:
Always completely power down the system before connecting or disconnecting LRUs
Use care when mating/un-mating connectors, especially network cabling
Observe and maintain proper voltage/current for external power systems — avoid surges/over/under voltages
Keep avionics master switches offwhen not required
The MD Explorer with Universal Avionics is coming soon to a flight department near you.