Military pilots train constantly to fly fixed-wing and rotary-wing aircraft in all conditions and perform multiple roles while doing so. As the technology continues to advance, more avionics and displays are plugged into a cockpit to help pilots have complete situational awareness and maximum operational capability.
As the missions are often complicated, bad weather develops, or aggressor aircraft enter the equation, a pilot has to stay engaged in what is going on outside the cockpit and cannot afford to get lost looking down at gauges and monitors.
A helmet mounted head-up display (HUD) is an invaluable tool for pilots of fixed-wing and rotary-wing aircraft. The HUD, which is mounted at eye level in front of the pilot, displays important flight information like engine data, flight operations, fuel status, armament condition, weapons targeting, and several other key information points critical to successful operations.
Helmet mounted displays (HMDs) have been around since South Africa developed a simple helmet mounted sight to help their pilots aim heat seeking missiles in the mid-1970s. Since then, HMDs have evolved to now include optical displays that present a pilot with critical flight information as well as controlling weapon systems.
Helmet Mounted Display in Attack Helicopters
Attack helicopter HMDs allow the weapons systems to be slaved to the pilot’s line of sight. This allows the pilot to see critical information on their head-up display. Slaving the systems to the pilot’s line of sight like this means all a pilot needs to do is turn his head to the target and shoot.
OH-58A/C Kiowa HUD HMD
An example of a helmet mounted display is the ANVIS/HUD of the OH-58A/C Kiowa helicopter. This HMD provides the Kiowa pilot advanced day and night display capabilities. This system also ties directly into the aircraft’s flight systems, superimposing the mission critical information over the night vision displays.
OH-58 sight display
Below is a symbology reference for an OH-58 HMD display. The sight display for an OH-58A/C is identical to the symbology on the CH-47D Chinook Helicopter.
| Pitch Ladder|
 Bearing to Waypoint
 Heading Tape
 Lubber Line
 Roll Scale
 Roll Pointer
 Baro Altitude
 Program Message
 OK/Fail Message
 Hover Vector
 Rate of Climb Caret
 Digital Radar Altitude
 Minimum Altitude Warning
 Radar Altitude Tape
 Radalt and ROC Scale
| HUD Fail Warning|
 Horizon Line
 Display Page Number
 Engine Torque Limits
 Engine Torque
 Aircraft Reference
 Engine Temperatures
 Distance to Waypoint
 Bearing to Waypoint
Repairing a Optical Display Assembly NSN: 1240-01-450-7545 P/N: 8506584-904
The optical display assembly of the OH-58 Kiowa is a compact sighting device composed of a panoramic telescope, mount, and adapter. This sight unit is usually used for pointing a weapon for direct or indirect fire. it may be attached to, or used in conjunction with, a weapon, rocket launcher, or the like.
In the photos shown above, an optical display assembly was repaired by Duotech Services technicians. The housings of these sight units were broken and needed to be replaced. Duotech’s fabrication shop milled glass filled plastic to produce a new housing unit within precise tolerances to meet the required specifications. The electronics were replaced and the identity serial number label moved from the damaged items to the newly manufactured housing units. These damaged units were repaired and returned to the end user to be put back into service with the OH-58.
As this example demonstrates, one of Duotech Services’ advantages over other repair station depots is our in house machine shop. It is a capability that allows us to serve our customer by providing unique item production, rapid prototyping, and replacement of damaged or missing parts that are hard-to-find or no longer available for purchase.
This in-house, solutions-based addition allows us to provide repair services quickly and within budget, to the exact specifications of the aerospace and defense industry.
Maintaining critical electronics, avionics, and radar systems of aircraft like the OH-58 Kiowa ASN-142, UH-60 Black Hawk’s AHRS, an F-16 Fighting Falcon’s Pulse Doppler Radar, and even the HUD of an F-5 Tiger II are essential to a nation’s security.
Duotech has over 34 years of experience providing a full range of equipment repair services. We provide Depot Repair Services for a wide variety of electronic and electromechanical systems for military and commercial applications. Find your part and contact us to answer your questions or Request a Repair Quote.