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Do You Need An NVG Inspection?
At Night Flight Concepts, we offer in-depth aviation NVG services and inspection procedures. Our highly-trained and experienced technicians utilize calibrated testing equipment and state-of-the-art inspection, servicing and repair methods.
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In-Depth NVG Inspection
Part of our 180-day inspection is a complete and comprehensive assessment of every component of night vision goggles: battery pack, helmet mount adapter, goggle adjustment rages, gain, current draw, image distortion, high/low light resolution, infinity focus, image intensifier, eyepiece diopter settings, binocular collimation, purge and low battery indicator function.
Once we complete the NVG 180-day inspection, we will return the night vision goggles complete with a test data sheet, airworthiness compliance certificates, and an NVG maintenance logbook.
Accurate Performance Measurements
Another key service feature we provide is performance measurements for all aviation NVGs. As the night vision goggles come through our inspection facility, we measure their performance and enter the data we collect in our database.
We will then conduct a continued accumulation of data as the goggles rotate through inspections. This step allows us to develop a trend analysis which helps us determine certain NVGs that may be aging and showing signs of reduced performance over time.
Professional Aviation NVG Repair Services
Whether it’s operational defects or cosmetic blemishes, our aviation night vision goggles repair services specialists are experienced and highly trained to handle any NVG issue you may have. If you see any blemishes or defects on your goggles, send them our way for proper inspection or repair. Please complete our shipping form and send it along with your NVG.
LOOK FOR COMMON NVG FAULTS
PRIOR TO EACH FLIGHT
Operational Defects
Operational defects are an immediate cause to reject NVGs for use. Once detected, the NVGs must be returned to our facility at once for evaluation and repair. These are the four operational defects NVG users should watch for:
Shading
If there’s shading, you won’t see a full circular image. This situation is caused by a defective vacuum seal of the image intensifier, indicating a dying photocathode.
When there’s shading, it’s completely dark and there’s zero visibility of images through the shaded area. It typically begins on the edge and migrates inward eventually across the entire picture. Shading is a high contrast area with a distinct line of demarcation.
However, don’t confuse shading with variations in output brightness. Improper sight adjustment and focusing procedures can also result in the false appearance of shading. Send your NVG to us if you suspect that there’s shading. We can carefully inspect it and correct any shading issue.
Edge Glow
If there’s an emission point (or a series of emission points) outside the field of view or by a defective phosphor screen that permits light feedback to the photocathode, then your NVG should be checked for edge glow.
To do so, you’ll need to cup a hand over the objective lens of the NVG. If the image monocular assembly is displaying edge glow, then the bright area will remain visible. Remit your NVG to Night Flight Concepts so we can check them for edge glow.
Emission Points
When checking for emission points, make sure that it’s not just any light source in the viewed scene. Emission points don’t go away when all light is blocked from the objective lens of that monocular. It can either be a steady or fluctuating pinpoint of bright light in the image area.
When checking for emission points, place a cupped hand over the objective lens to block out all light. If the bright spot remains, submit the night vision goggles to Night Flight Concepts to undergo further checking.
Flashing, Flickering, or Intermittent Operation
The image may appear to flicker or flash, either in one or both monocular. You can commonly see these flickering when adjusting the eye-span knobs. If you experience multiple flickers, check for loose wirings, battery caps, or weak batteries.
For any flashing, flickering, or intermittent operation, send off your night vision goggles to us for a comprehensive inspection. Make sure to indicate the amount of flashing or flickering on our inspection and maintenance form.
Cosmetic Blemishes
These are usually manufacturing flaws. Cosmetic blemishes found in night vision goggles don’t necessarily render them ineffective; these flaws do not have any effect on the image intensifier reliability. Nevertheless, some cosmetic blemishes can worsen over time. And while these blemishes are not usually a cause for rejection, they can get severe enough that they interfere with the performance of the goggles.
If you find any blemish in your NVG, document the specific nature of the problem on the provided maintenance forms. Identify the position of the defect by using the clock method and approximate distance from the center (e.g., 5 o’clock toward the outside, 2:30 near the center, or 1 o’clock midway.) You may then return the NVG for repair to our FAA Part 145 NVG Inspection and Repair Station.
Here are some of the most common cosmetic blemishes you should look out for:
Bright Spots
Flaws in the film on the microchannel plate can cause bright spots in the image area. These spots are usually small, non-uniform, and bright. They may flicker or appear constant, and they typically go away when the light is blocked out.
To check if any bright spot you see is a cause for concern, place a cupped hand over the objective lens to block out all light. If the spot remains, there’s a likelihood of the existence of an emission point. You may then send the device to us for further checking.
Output Brightness Variation
This is characterized by areas of varying levels of brightness in or across the image area in an individual monocular. The lower contrast does not show distinct lines of demarcation. They also don’t degrade image quality.
For more information about our NVG inspection and maintenance repair services, please fill out our contact form so we can properly assist you.
Image Disparity
This condition may exist when there is a difference in brightness between the two image intensifier assemblies within the same binocular.
Veiling Glare
When light outside the field of view strikes the objective lens of a night vision goggle and scatters rather than passes straight through the lens, then something called veiling glare occurs. This condition produces a reduction in contrast and occurs only under certain circumstances.
It may be caused by excessively scratched, pitted, or chipped objective lens. Additionally, dust and fingerprints may affect this condition. Thus, you must ensure that your lens is always clean.
During a routine NVG preflight inspection, veiling glare may not be immediately evident. Our highly trained and experienced specialists will thoroughly check for veiling glare to see if the image intensifier or objective lens will need to be replaced.
Image Distortion
Do vertical objects such as trees or poles appear wavy or bendy when looking through your NVG? If so, then your goggles should be screened for distortion. We recommend each image intensifier be checked before the first use.
All Night Flight Concepts aviation NVG undergo a detailed and meticulous quality assurance check prior to delivery.
Black Spots
These are usually dirt or debris stuck between the lenses. Generally, you can assume the black spot was there during acceptance. However, occasionally the need may arise to verify location, size, and number of spots against the allowed specifications for the image intensifier.
Chicken Wire
These are irregular patterns of dark lines found all over or in parts of the image area. Under the worst-case condition, these lines may form a hexagonal or square-wave shaped lines. These lines exist due to the defective fibers not transmitting light at the boundaries of fiber bundles in the output optic of the image intensifier.
Fixed Pattern Noise
This is characterized by hexagonal patterns throughout the viewing area that usually occurs at high-light levels or when trying to view extremely bright lights. All NVG image tubes will display fixed pattern noise if the outside lighting output is high enough.
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