Decisions, Decisions

During the past month and a half one of the helicopters my other employer operates underwent all the trials and tribulations associated with a major inspection. This also included numerous component overhauls.

The mission of this machine is multifaceted and in addition to VIP transportation, a significant amount of operating time is devoted to wild game management. We planned to take advantage of this maintenance event to have a company radio installed along with a new portable global positioning system (GPS).

None of my previous aviation lives yielded any significant rotary wing experience so I was looking to this occasion as a learning situation. Fortunately, I work with some very knowledgeable people and most of the technicians employed by the helicopter manufacturer’s authorized service center have more grey hairs than I do. The prospect of installing a radio and GPS during the inspection did not appear to generate any concerns. Like with any other project of this magnitude we devoted a significant amount of time to research and planning. Standard practices used by the airframe manufacturer were reviewed, tech reps were contacted, the work-scope was finalized, and a timetable was created.

Installing GPS system/radio

The portable GPS had been selected on the premise it could be used in the helicopter while surveying various areas as it contained road maps along with geographical highlights and points of interest could be saved as waypoints. In addition to position information, this device could receive digital weather information and pertinent flight advisories that would be displayed to the observer along with warning of power lines. Data base updates can be purchased from suppliers such as Jeppessen for aviation information. There are of course information packages for a road atlas and even nautical charts. In order to load this information in the GPS a patch cord, tethering it to a laptop, is required along with Internet access.

An annual subscription service for XM Satellite Radio is available allowing the helicopter occupants to listen to news, sports, and music. When the aircraft lands, the device could be removed and transferred to an all terrain vehicle which could then return to the noted waypoints at a later time. The plan was to utilize 28-volt aircraft power converted to the 14 volts for primary operating power plus a charging source for the device’s internal battery.

When operating outside the aircraft the battery was intended to allow continuous operation for up to eight hours.


While perusing the accompanying operating manual, I noticed a paragraph written in bold print starting with the word “WARNING.” Of course my previous years of being involved in aircraft maintenance has provided me with keen insight, having learned (in some cases the hard way) that failure to pay attention to such things sometimes can be painful and always expensive. In any case, I figured if I did not read the entire manual, I should at least read that one paragraph. It was outlining the possibility of overheat by the lithium-ion battery along with the possible result of prolonged exposure to heat.

Gee, we planned to operate this thing in the desert during the summer months. I wonder if that will be a problem? Being a firm believer in Murphy’s Law, I knew it would!

Fire regulations

The Federal Aviation Administration (FAA) has seen fit to issue Advisory Circular 120 – 80 which is titled “In-Flight Fires.” In my opinion this is a piece of information that should be required reading by everyone involved with aircraft. It does contain an area where various flammable substances are listed and recommended types of extinguishing agents to use.

On Jan. 5 of this year the FAA published an additional document related to in-flight cabin fires. This document is in the form of a “Safety Alert For Operators” (SAFO). The subject is specifically in-flight fires caused by lithium batteries. The background of the document reads:

“There have been several occurrences of smoke and fires erupting from failures of lithium-ion batteries such as those used within laptop computers. A more recent incident involved a lithium battery powered portable air purifier which caught fire resulting in injuries to several passengers and diversion of the flight. The NTSB is investigating this incident. Such batteries tend to electrically short and quickly overheat when rapid discharging or unregulated charging occurs. One prominent battery manufacturer, recently highlighted in the media, produces a “regulated” battery type that has been subjected to recalls after several cases where battery failures caused fires. Other battery manufacturers, who produce “unregulated” batteries which provide higher capacity (such as those used in cameras, electronic games, medical equipment, flashlights, air purifying devices, etc.), are not necessarily aware of their vulnerabilities. Thus, the probability for such battery failures resulting from overheating caused by rapid discharging is higher with unregulated types in greater number of uses.”

The SAFO goes on to recommend that all crew members be properly trained in recognizing the type of fire and then choosing a suitable extinguishing method. In the case of lithium batteries, halon will have no effect on the shorting battery but may prevent fire spreading in the surrounding area. Only a category “D” extinguisher will have a positive impact on this type of combustion.

Battery testing research

There are published results derived from FAA sponsored testing of lithium batteries and in summary the results state:

Primary battery major findings

  • A relatively small fire source is sufficient to start a lithium battery fire.
  • The ignition of a single battery produces enough heat to ignite adjacent batteries.
  • Halon 1301 is ineffective in suppressing a lithium battery fire.
  • Batteries of the same type but from different manufacturers exhibit varying flammability characteristics.

The entire report can be accessed on the internet at

Technical Standard Order (TSO) C-179 was issued Aug. 4, 2006 and the purpose states: This TSO affects new applications submitted after its effective date. Major design changes to rechargeable lithium cells and lithium batteries approved under this TSO will require a new authorization. See Title 14 of the Code of Federal Regulations (14 CFR) § 21.611(b). The method of testing these batteries is one of the highlighted items (See table below).

Tests for Fire Safety Requirements
Criteria to Pass
External short circuit Measure direct connection between terminals through electric wire with resistance of 2m-ohm. State of charge (SoC) of a cell: 100% No venting of gases/vapors. No smoke produced. No ignition or fire. No explosion.
Crush Test battery by dropping an iron ball (9.1 kg) from the height of 61 cm. SoC of a cell: 100% No venting of gases/vapors. No smoke produced. No ignition or fire. No explosion.
Over discharge Test battery by discharging with a current of 1A for one hour (or to the maximum discharge time for the battery operation). SoC of a cell: 100% No venting of gases/vapors. No smoke produced. No ignition or fire. No explosion.
Overheat Test battery by heating up to 115 C in the oven. SoC of a cell: 100% No venting of gases/vapors. No smoke produced. No ignition or fire. No explosion.
Fire Test equipment unit with battery in place for fire penetration by igniting a single unit. SoC of a cell: 100% Unit must contain the fragments/debris from explosion but not gases/vapors/smoke. Fire within the unit must self-extinguish. Note that a fire-extinguishing or suppression system outside the battery (such as in the equipment compartment) may be used to provide this feature if the system is designed to handle this fire threat.

Installation challenges

Based on the above criteria, our resolve was to make sure the battery was not installed in the GPS during flight operations. It would only be installed prior to aircraft power shutdown to retain the waypoints and then of course would be used on the ground vehicles as loose equipment that could easily be jettisoned in the event of fire. Recharging of the battery was accomplished by a car charger during ground operations.

Another challenge encountered was how to make the XM Satellite Radio available to the cabin occupants. In this aircraft all passengers wear headsets and all internal communications is through the aircraft intercom system. Unfortunately, the audio amplifier was a bit antiquated so a direct patch in through a switchable control was not possible. After consultation with the flight crew, it was decided a direct input was to be made to the intercom panel just like a passenger headset so any crew comments or ground to air communications would automatically take precedence and the XM volume control was to be used as the only cutoff control. It worked as advertised.

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.