A Look at Avionics Upgrades

At some point during the lifespan of a helicopter, a decision is made to upgrade or modify the airframe, the engines, the avionics systems or some combination thereof. That’s when the helicopter’s owner, flight operations manager or director of maintenance will come to my shop to see what choices are available to upgrade and/or modify the aircraft.

Upgrade vs. Modification

An “upgrade” refers to the removal of one system from the aircraft and the installation of a newer and better one in its place. The new system may have the same manufacturer as the old system, but consists of a more advanced product with better capabilities. For example, the customer might be looking at removing the existing phone system that is only capable of making two phone calls at a time to a phone system that allows several users to make different calls to different numbers at the same time, and includes the potential for Internet service.

On the other hand, a “modification” consists of only a partial alteration to the existing system and does not necessarily require its removal. For example, the customer might keep the existing phone system, but wish to add a few more handsets.

Upgrade Benefits

Most customers usually choose to upgrade their aircraft rather than modify it. That is in large part because an upgrade typically adds value to their aircraft, and generally provides better performance than a modification.


The importance of an upgrade usually depends on whether it’s an upgrade that is an FAA-mandated requirement in response to an airworthiness directive (AD), whether the upgrade would increase the performance of the aircraft, or if the upgrade would improve a passenger convenience item (often something that the owner just has to have.)

Exploring a WAAS/LPV Upgrade

The Duncan Aviation-Teterboro avionics shop recently completed an upgrade for an operator who wanted to increase the performance of his helicopter by adding a Wide Area Augmentation System/Localizer Performance with Vertical Guidance (WAAS/LPV) system.


The FAA completed and certified a significant upgrade to the GPS system in 2007. The WAAS system uses a network of more than 25 strategically-positioned precision ground stations to provide corrections to the GPS navigation signal. WAAS is designed to provide the accuracy, availability and integrity necessary to allow flight crews to rely on GPS for all phases of flight, from enroute through GPS precision approach for all qualified aircraft within the WAAS coverage area. This provides a capability for the development of more standardized precision approaches, missed approaches and departure guidance for approximately 4,100 ends of runways and hundreds of heliport/helipads in United States airspace. WAAS also provides the capability for increased accuracy in position reporting, allowing for more uniform and high-quality worldwide air traffic management. WAAS is a critical part of the FAA’s NextGen program along with GPS LPV precision approaches. LPV approaches offer the lowest minimums of GPS systems.

With NextGen deadlines in place, WAAS/LPV upgrades are something many operators are considering. The first step in evaluating such an upgrade is to take into account what type of aircraft the customer has and what avionics are currently installed.

In the second step, we would do research to see if there are any STCs available that the FAA has previously approved which would suit the needs of the customer’s aircraft upgrade. All avenues are explored at this time. Items for consideration include:

• Do the line replaceable units (LRUs) have to be sent out or totally replaced?

• Is there enough space for mounting new units?

• Will adding more of a load to the existing electrical power system cause any issues?

• Can the aircraft handle any additional weight that may be involved? (Helicopters tend to be more weight-and-balance critical than fixed-wing aircraft.)

With all these questions answered, the next step is to develop at least a couple of options for the customer to review. Going over the benefits and drawbacks of each, we strive to help them choose the best option for them and their flight requirements.

Once the customer chooses the option that best suits their needs, a timeline of the upgrade is determined and a project timeline is set.

Planning the Work

Even though the aircraft is not scheduled in for a few weeks, a massive amount of work must be done before the aircraft installation can begin. Most people don’t understand the extent of this planning work. The parts for the installation have to be ordered and accounted for. Any outside vendors that may need to work concurrently during the aircraft’s downtime will need to be scheduled with the proper workflow.

While the scheduling details are being completed, the engineering department starts drawings that tie all the required systems together. Once they are finished, these documents are sent to the FAA for approval. This process could take weeks by itself and we cannot actually start work on the aircraft until the approvals are received.

The Upgrade Itself

Once the upgrade itself begins, access to all areas that will have work done must be available. Interior pieces are removed and properly protected, and old units that are removed are tagged and stored. The upgrade team schedules work in a manner that makes the most effective use of time. Wires are labeled, run alongside and attached to existing wire bundles according to aviation standards. If airframe work, such as an antenna doubler needs to be installed, time will be saved if that can happen concurrently with the wire running. When all the wires are installed, a verification of the wires and their correct routing is performed by ringing them out with a multimeter.

After the units themselves are installed, power-on checks can be started. Depending on the system being installed, a flight test might be required. After all this has been finished and everything passes the operational checks, the final paperwork can be completed and the aircraft can be returned to service. Copies of the paperwork will be sent to the FAA and kept on file with Duncan Aviation. The originals are given to the customer for their records. At this time, the aircraft upgrade is complete.


The Results

The new system gives the aircraft new capabilities and with today’s technology, the system is more reliable and makes the failure rate low. A low failure rate means less downtime and more income to be earned for Part 135 operators.

From a maintenance standpoint, most of the newer digital systems are more technician friendly, as opposed to the older units. Today’s newer avionics systems are either laptop accessible or have a better diagnostics program to help in troubleshooting in case the system should fail. This will also lower downtime rates and increases the availability of the aircraft for flights or charter.

Upgrade versus modification, a choice that comes along more often than not. Have you had a recent upgrade performed on one of your helicopters? How did it affect the overall performance or capability of the helicopter? Let us know. We would very much like to hear about it.

Jeff Glanville is the manager of Duncan Aviation’s Teterboro, N.J., avionics satellite shop. He has been with Duncan Aviation for 10 years. Glanville started his aviation career in 1992 in the U.S.A.F. as an F-15 avionics technician. Upon his discharge, he worked for Garrett Aviation in Long Island, N.Y., as part of the installation avionics crew.