The skyBeacon TSO is an accessory for non-commercial aircraft that allows an older plane to be easily retrofitted with ADS-B out functionality. Starting in 2020, the FAA mandated that all civil aircraft must be equipped with ADS-B broadcast equipment to fly in most controlled airspace. ADS-B broadcasts consist of a unique identifier (tail number), aircraft type, velocity, altitude, and position. The skyBeacon TSO monitors a pre-existing transponder in the aircraft for mode A/mode C replies. It then broadcasts ADS-B information to bring the aircraft up to the level of compliance required by the FAA. The skyBeacon is mounted on the wing-tip and includes several key features: a wireless receiver for the transponder signals, a transmitter for ADS-B out, a Wi-Fi communications module for programming, an LED position light, an LED anti-collision light, a barometric pressure sensor (altitude), and a GPS receiver. All of that is combined into a small plastic package that mounts on the wing tip in place of the existing anti-collision/position light. It uses just three wires: a ground, a power input for the transponder and lighting, and a control wire for the anti-collision light. This particular skyBeacon met it's demise when a high voltage strobe wire broke free from a solder joint during landing and made contact with the airframe. This caused a high voltage surge to damage the power regulator section of the skyBeacon. Unfortunately, there is little protection (such as a fuse) built into the skyBeacon. There do appear to be reverse-polarity protection diodes, but this does not do much to prevent damage from a high-voltage spike.
The top side of the skyBeacon that faces the sky is where the GPS receiver is mounted. It is clearly visible through the transparent plastic casing.
On the back of the skyBeacon is a metal mounting plate that secures the unit to the airframe. As mentioned earlier, there are just three wires. Black (ground), red (electronics and position light power), yellow (anti-collision light control signal).
The transparent plastic cover can be removed by undoing the 7 torx screws. It keeps the enclosure sealed and has reflective portions that help direct the LED light.
With the plastic cover removed, we get our first glimpse of the motherboard. It's a red PCB with a white daughterboard soldered to it.
With the screws removed, the metal plate also pulls away from the plastic assembly. There is a small plastic piece which the wiring runs through. This pulls away from the assembly and allows the wires to be pulled through the frame.
With the front and back covers removed, the electronics can be slid out. The antenna section of the PCB extends into the fin-shaped part of the casing. A small strip of white plastic wedges between the PCB and main plastic enclosure to keep it from moving around when the unit is fully assembled.
This is the complete electronics module which contains the motherboard PCB with integrated antenna, anti-collision lighting daughterboard, and the GPS antenna connected via a small coax.
The most notable components on the daughterboard are the anti-collision LEDs. The position LEDs are located in the motherboard.
The daughterboard is soldered via a dual-row pin header to the motherboard. We accidentally melted a plastic support when using a hot air station to separate the two boards. Not a very serviceable design as the solder pads are extremely small and would be difficult to get to with a soldering iron.
Here is the motherboard with the daughterboard removed. There are some interesting RF transmission components on this side along with the PCB antenna.
Taking a closer look, there are several notable components on this side of the board. Directly below the pin-header is an STM32F microcontroller. Next is a Skyworks SKY65313-21 900 MHz transmit/receive front-end module for RF communications. Next is a Ping PF007 which appears to be a custom (or rebranded) part from uAvionix that is designed to receive ADS-B traffic. Towards the center of the board is a NXP AFT09MS031 RF power transistor.
On the other side of the motherboard is where things get interesting. There are two common, off-the-shelf components on this side of the board. First is an ESP-12S module which is a favorite amongst electronics hobbyists and commonly found in IoT devices, but not a component we would expect to see in a piece of avionics. The ESP-12S has a 32-bit MCU, built-in Wi-Fi, Bluetooth, and various GPIO connections. It also supports various serial interfaces such as I2C, SPI, and UART. In this unit, the ESP-12 is used for the Wi-Fi communication and may be acting as the central processor of the skyBeacon. The next off-the-shelf component is a uBlox NEO-M8T-0-10 GNSS (GPS) receiver module. This is a common part that can be found in many devices that require the use of GPS positioning and timekeeping. Connected to the uBlox receiver module is a small GPS antenna manufactured by TAOGLAS. Positioning information obtained from the GPS receiver is part of the ADS-B broadcast.
Here is a closer look at the power input and regulation section. There is no physical damage to any components on the board from the surge. It's very challenging to trace connections on this board due to its modern and complicated design. It is very likely that one or more of the surface mount regulator components have been destroyed. When 14 VDC is supplied to the unit, it draws essentially no current and none of the lower voltage rails such as 5V and 3.3V are active. We did try supplying 3.3V directly to the ESP-12S and got it to power up. The status LED flashes and we were able to see the Wi-Fi network SSID being broadcasted. Unfortunately, it's not really feasible to repair this unit to an extent where it would be reliable enough to be re-installed in an aircraft.
We have linked some information below if you'd like to learn more about this unit or its components.