NVG Systems 101
Night vision goggles (NVG) operation, backed by an FAA-approved NVG modification and training, is the safest way to fly at night. The cost for doing so is admittedly cost-prohibitive for recreational users. However, professional pilots flying for EMS, law enforcement and other critical missions, NVG operations are significantly less costly then losing the aircraft, crew and possibly some patients.
The most common myth about using NVGs is that they are utilized for viewing the cockpit instruments during flight. In reality, the helmet-mounted goggles are set for viewing the outside darkened environment, allowing instrument viewability by scanning under the goggles tubes with the unaided eye. NVGs operate efficiently by harnessing environmental infrared (IR) from ambient light sources, amplifying the IR to a level that provides night vision capabilities.
Any NVG modification in the cockpit is designed to minimize internal IR energy from cockpit light sources. Excessive internal IR will cause the NVG’s to ‘bloom’ reducing their effectiveness as a high technology tool.
This section will assist you in the search for NVG modifications, while providing the pros and cons of several methods available today. In addition, we’ll discuss FAA requirements, training options and NVL installation.
So what makes REB Technologies (REBTECH) the experts in NVG lighting? The answer is experience: Between them, REBTECH corporate management professionals, Dick Borkowski, Richard Borkowski and Jeff Stubbs have more than 50 years of NVG lighting knowledge and know-how. Their experience encompasses all sectors of the NVG lighting including instrument design, edge-lit panel fabrication, switch/annunciator detailing and to aircraft installations. In addition we enjoy an in depth back ground and knowledge for NVG test equipment needs allows the customer to take advantage of the true “one stop shopping” experience. At REBTECH, we believe that our capabilities and hands on experience offer our customers the best range of NVG lighting options and innovative solutions.
History of Night Vision Lighting
Night Vision Lighting (NVL) was implemented after the release of MIL-L-85762A in the early 80’s. Due to the technology and limitations of the goggles available at that time, infrared light had to be eliminated entirely from the cockpit. This caused the development of NVG green filters to cover cockpit instruments. Unfortunately, the green filters allowed 12-18% of visible light transmission that completely saturated all other colors in the instruments. The poor color definition and color saturation contributed to a significant number of accidents and in some cases loss of life.
In addition to transmission and color saturation issues, NVG green filters had other problems that the MIL-L-85762A specification didn’t take into consideration. For instance, to make instruments comply with the specification, the instrument cover glass, dial, pointer and warning flags had to be reconfigured with new materials and paints formulas compatible with the NVGs. Needless to say, this was a very costly process. In addition, instruments models varied from aircraft to aircraft and required additional engineering time to insure instrument compatibility. Instrument external filtering wasn’t the end all we anticipated again, since the available green filters had such low transmission making the instruments scarcely unreadable during both night and daytime flight operations.
During this time period many operational aircraft utilized post light and/or flood lighting in lieu of internal instrument illumination. This scenario created a new set of problems. Although these lighting components met the intent of MIL-L-85762 as a standalone component and were easier to install, they exhibited many of the same problems that were evidenced by the use of green filters for direct instrument modification (internal and external). In addition, post lights regardless of their NVG compatibility caused canopy reflections detrimental to the goggle effectiveness. As a result, NVL aircraft modifications were a constant struggle. Due to the available technology, pilots just had to make do with whatever was available to them. Many pilots developed their own NVG compatibility blacking out various displays with duct tape, electrical tape, or adding plastic film filters and chemsticks. These initiations and other pilot innovations negated the full function of the instruments so critical for safe flying conditions and demanding that the pilots rely on their own skills rather than the instrumentation in order to fly.
In the early 90’s multi-color displays began deployment in many new aircraft most notably in special ops aircraft; posing an entirely new challenge to NVL. In 1992, Jeff Stubbs developed a low profile portable bezel (SHADOWS™ Screens) that could be easily installed or removed from a multi-color displays. This component was similar in design to what Jeff developed for flight and engine instruments. This innovation was a giant step forward in lighting efficiency and allowed discrete cockpit instruments to maintain their generic identity.
In 1996, NVG White lighting components were starting to take shape and so was REBTECH. Company owner Dick Borkowski wanted his company to break away from tradition and explore new technologies. Having seen firsthand the problems with NVG green filters, the inconsistent application of MIL-L-85762, and overpriced NVG products, Borkowski wanted to supply an inexpensive system to military and civilian pilots alike. He was aware that many pilots were flying in blackout conditions due to lack of funds or the availability of cost effective lighting solutions.
It didn’t take long for REBTECH to introduce a dual powered battery/aircraft NVG Blue/White LED portable system. Reasonably priced, the SPIDER LIGHT system would illuminate critical displays of B-1 bomber instrument panel designated by the flight crew. The first response from the pilots was ‘wow; get the incredible looking cockpit with the white lighting!’ They were now able to identify the range markings on their instruments and have a clear look at their flight control status immediately. They credited with white lighting for minimizing eyestrain that was inherent by the low transmission of green lighting.
SPIDER LIGHT led REBTECH into the civilian marketplace, resulting in the development SHADOWS™ Filters. The SHADOWS™ clear filters allowed for internal filtering of instruments, eliminating the saturation consistent with green filter modifications. Around the same time SHADOWS™ color filters became available which allowed exterior devices such as solid state ADIs and HSIs to exhibit the same high transmission modification. In addition, REBTECH made available utility lights in NVG White for map reading and edge-lit panels. Finally, after years the REBTECH NVG clear lamp came into being, allowing for efficient and balanced modifications of existing annunciators and illuminated switches.
It is our belief that SHADOWS™ Filters were the leading factor when the FAA decided to approve NVG White in lieu of MIL-Spec NVG Green Lighting. To the best of our knowledge, the first white lighting system was installed on the Bell Helicopter Training Academy’s Bell 206 which then followed by the Tucson Police Department installing the same system.
FAA Requirements for Part 91, 135, and 141 Operations
After several years of working on how to approve and regulate NVG operations, the FAA has established a logical set of guidelines for acceptable filtering. Unfortunately, there are those offering NVL services that do not adhere to these guidelines. Therefore it is therefore necessary to review the Advisory Circulars for clarification and direction. Should the FAA find a violation the result may lead to your aircraft being grounded.
Operations: Aircraft users must be NVG qualified and have a system in place for initial and recurring NVG training. At present, there are several FAA-approved NVG Training Academies. Bell Helicopter Textron established the first airframe sponsored training school followed by Airbus, both located in Texas. Independent training schools have been established including Night Flight Concepts with a Florida home base. All three mentioned herein offer an outstanding syllabus and training regimens.
Equipment: Night Vision Goggles must be qualified IAW TSO-C164.
Aircraft: All must have STC-approved NVG kits and Radar Altimeters.
Supplemental Type Certificates (STC)
The FAA has determined that an STC is required for an NVG modification. Renaming the modification to “Alternate Lighting” or any variation is not permissible to get around accomplishing an STC.
The NVL manufacturer/supplier is responsible for gaining STC approval, and when a kit purchase is executed a copy of the STC is included and should include a Flight Manual Supplement (FMS), and Instructions for Continued Airworthiness (ICA). These actions will necessitate an entry into the aircraft’s log.
The application, installation, and testing of an STC should not adversely affect the aircraft operator. Should a NVL modification be awarded to manufacturer without an STC for your particular aircraft model, then appropriate action will be required to quickly and efficiently acquire your STC.
To determine if your NCL supplier has the appropriate credentials to satisfy your needs, we suggest that you refer to the FAA’s website. This will allow you to look up issued STCs by vendor to validate their capability. This will also provide you with insight on the timing required by FAA for the approval of existing and new STC applications. Once the STC process begins, here are a few of the key steps:
1) Documentation submittal
2) Hardware installation
3) Test flights; Day & Night evaluation
4) Return the aircraft to service
5) FAA issues the STC
The aircraft will have to be moved to “experimental” status, and then returned to service after the test flights are successfully completed. The aircraft user will need to have an NVG qualified pilot available for the test flights.
Gaining an STC for a NVG modification is truly a team effort between the FAA, the aircraft operator, and the NVL supplier. This said, there is no reason for the aircraft to be out of service for more than two weeks. REBTECH has received nine STCs to date for more than twenty-nine aircraft models and has never had an aircraft grounded for more than 10 days.
If you are going through the STC process, be sure that you and your NVL installer have addressed every issue involved in acquiring a new STC. The two essentials for a successful STC application are employing appropriate NVL hardware/techniques and proper planning. If one of these is not coordinated or done in a timely manner, the STC process could take months rather than days.
Public Use Aircraft
There are no specified requirements for incorporating NVL in public use aircraft. However, if you are flying NVG operations in a public use aircraft, REBTECH suggests modifying your aircraft using STC-approved practices. The additional cost of an approved modification is still significantly less expensive then a new aircraft and/or crew resulting from an NVG incident. In addition, your insurance premium may be favorably impacted.
Pros & Cons of Various NVG Modification Methods
A major part of any NVL modification is the quality of filtering directed at the flight and engine instruments. Listed below are several approaches that are currently in use today modification. The decision on how to implement the modification depends on several factors including mission, safety, existing STCs, aircraft model, and budget.
Incandescent Post Lights
Incandescent post lights are inexpensive components; easily repairable the first few times. However, the post lights will eventually become loose and cause lighting issues. The technology has not developed over the past 50 years and although the post light meets the Mil Spec., the illumination produced is much less than what is required for filtered indicators or displays. In addition adding new post lights to existing wiring may also present problems.
LED Post Lights
LED post lights are a one piece construction as opposed to incandescent post lights. The upside is that the single piece unit eliminates the problem with the head of the component becoming loose. LED post lights should last the life of the airframe. However, should the LED malfunction, then the entire assembly has to be replaced. Another issue with LED post lights, particularly on rotorcraft, is that an improper LED post light installation can cause the post lights to shutoff during startup.
At first glance, post lights appear to make for a quick inexpensive fix. Installation time including wiring panel alteration is time consuming adding to your labor costs. All holes drilled into the instrument panel are unsightly should the modification ever be removed and the aircraft sold. Overall the lighting is a poor NVC solution, since post lights are light sources and external to the instrument. In addition, they typically dim at a significantly different rate than the other equipment in the cockpit when added to aircraft dimmer systems.
The instruments affected by the post lights must be separate from the lighting circuit. There are several methods of doing this but there has to be assurance that the instrument’s internal lighting is disabled during NVG operations.
This technology was developed in the mid to late 1980’s and was a band-aid option (a less than optimum solution) during a very difficult period in NVG lighting progression. Basically a bezel-ring light is a thin edge-lit panel designed to fit around the instrument and floodlight the instrument’s face. It requires either an instrument mounting screw to be removed to run the wires to the aircraft harness, or holes to be drilled in the instrument panel.
There are several variations to this solution, including a one piece assembly that fits over all of the instruments. Problems with the one piece assembly include excessive weight; no way to add new equipment without buying a new assembly, and the replacement of burned out lights requiring significant down time. The increased thickness diminishes visibility and can cause parallax issues. This is just a really expensive and inefficient way to work-around post lights.
When completed correctly, this is the best final product available. Internal modification allows the instrument to be serviced during the NVG process, the interior cleaned up, and new lamps to be installed. This approach results in clear crisp images in a reconditioned instrument (lighting works / instrument works).
Internal modifications are inherently more expensive than other modifications. However, when the price for internal modification is compared to other NVL solutions the delta difference closes dramatically. In addition special capabilities are not required for the lighting upgrade.
Externally mounted filters offer the quickest installation approach. It is not intrusive to the aircraft wiring, so aircraft downtime is reduced. External filtering does not affect the existing aircraft lighting system. It allows for balanced lighting, for night operations and satisfies sunlight readability requirements.
On the down side there are some suppliers that utilize a thick dark blue glass; resulting in poor daylight readability. Some of these filters can be fragile with breakage resulting from improper mounting. After installation, external filtering has proven to be very durable. The only negative is that the quality of the lighting is reliant on the instrument manufacturers’ initial lighting design for appropriate illumination.
For the remaining equipment, REBTECH replaces flight critical panels with NVL White panels. Caution & Warning, radios, and color displays receive a true color shadows filter. Utility lights, cockpit and cargo area dome lights are filtered or replaced with NVG White components. Switches and annunciators receive the new REB Technologies T-1 NVG White bulb for quick, easy replacement and modification.
Purchasing a NVG Modification Kit
Purchasing an NVG kit today has become a lot easier then in previous years. The FAA regulations have eliminated much of the guess work in selecting their NVL modification requirements. However, as with any product, a certain amount of research should be conducted before you make a purchase. As an aircraft operator, your most valuable resources are your aircrew, aircraft, time and expense. So assigning resources to ensure you are getting the best quality, service and value for your NVL modification is prudent and cost-effective in the long term.
One quick research resource is the aircraft’s manufacturer, Bell Helicopter and Airbus both have NVG flight training schools and both are utilizing REBTECH’s SHADOWS™ lighting kits. As previously mentioned, another option is to view the FAA website and search for STCs by company name. This will allow you to quickly decide who is able to turn an STC quicker and in line with the FAA requirements.
NVL modifications are too important and too involved to be left to newcomers and lowest bidders. Consider all of the factors and you will quickly come to the realization that the lowest bidder is typically higher cost!
Other points to think about
Consider the value of your aircraft; how much downtime can you afford for the installation?
How is internally modified equipment repaired; what’s the turn time?
Look for innovations in NVG Lighting. A company dedicated to lighting will always be driven for improvements.
Fleet owners should look for companies that can do fleet modifications, and who provide consistency between aircraft, because consistency enhances flight safety.
Can the NVL supplier train your staff to maintain the system after the installation is complete?
Does the NVL supplier have a reputable aircraft facility to install the NVG kits?
Is there more than one facility that can accomplish your installation?
Does your supplier have references? If so, contact them to discuss all aspects of the NVL upgrade including AC down time, pilot reactions, aftermarket support.
REBTECH proposals offer a one price solution. All documentation, hardware and travel expenses are all included in the REBTECH proposal.