Decisions, Decisions

Installing a radio and GPS system — what’s involved?


Radios and related regulations

The next endeavor was to install the new company communications radio. We had talked about using a handheld and determined per FAR 91 – 21 that this would be a possible solution as the helicopter does not operate IFR. The convenience of having the receiver transmitter be an integral part of the flight deck has advantage as most helicopter pilots have both their hands full most of the time and having to handle a portable radio would be difficult. A device was selected that is a programmable Ultra High Frequency (UHF) unit with a frequency range of 450 to 470 MHz and a maximum output of 50 watts. For anyone contemplating this kind of project, take my word that it is not quite the same as installing a Citizens Band (CB) radio in an automobile. After looking through what I considered the appropriate Federal Air Regulations (FARs) and making contact with individuals who had undertaken this sort of venture in the past, I finally felt I had the information needed to do this safely and legally.

One consideration here is that when it comes to communication equipment in aircraft, the FAA is not the only bureaucracy there is to contend with. The Airworthiness Inspectors Handbook addresses the Federal Communications Commission Radio Station License for aircraft and specifically states: An aircraft FCC radio license is required although the FAA does not regulate the requirement. The license may be for that particular N-number or a fleet license. The expiration date of the license is in the upper right hand corner.

The handbook also states that the inspector should bring any discrepancy to the attention of the operator. It should be noted that international operations do require a valid FCC license be carried on all aircraft. FCC Regulations pertaining to aviation are listed in Title 47 of the Code of Federal Regulations (CFR) Part 87 titled “Aviation Services.”

Lessons learned

I learned three important facts from my research and they are:

  1. Transmitters such as the one planned for installation must have their output power limited to no more than 10 watts.
  2. An FCC Aircraft Station License only covers Very High Frequency (VHF) Transceivers.
  3. The FCC is another bureaucracy.

Once the licensing issues had been resolved the radio was sent to an approved shop where the power output was reduced from the factory set 50 watts to the FCC mandated 10 watts.

Another gotcha can be the obscure notes that somehow become camouflaged within the aircraft Type Certificate Data Sheet (TC). One such note in the Bell 407 Type Certificate explains that due to the sensitivity of the Full Authority Digital Engine Control (FADEC) any system or component installed which produces a High Intensity Radiated Field (HIRF) must be tested to ensure there is no impact on the engine control. The real kicker here is that the means of testing has to be pre-approved by the FAA!

Choosing an ideal location for a radio antenna can be another befuddling ordeal. First of all, newer helicopters use a significant amount of composite material which may not provide an ideal ground plane. Secondly, any antenna on the lower surface may hinder radio operation while the aircraft is on the ground and an antenna mounted on upper surfaces may be masked by the operation of the main rotor. It is beneficial to obtain reliable guidance prior to locating and installing the antenna.

As I initially indicated, this maintenance event was intended to be a learning experience for me and without a doubt it was. I did decide that my original opinion about rotorcraft was unchanged. That lesson learned was clearly illustrated by the placard next to the tail rotor. It tells me all I really need to know about helicopters, “Stay clear!” That is my final decision.

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