The Eurocopter EC 145 has received the first certification for night vision goggle- aided civil operations. The European Aviation Safety Agency (EASA) certified the capability in May, and the FAA and Transport Canada (TC) are expected to follow suit this fall. The modification is available as original equipment and retrofit.
“NVGs are not certified on their own. What is certified is the adaptation of the helicopter cockpit to a particular set of NVGs. This is called a night vision image system [NVIS],” an EASA expert told AIN.
NVG-capability certification is quite restrictive. The certification is for a particular helicopter and a given set of NVGs. Each helicopter model will have to have its own certification. In addition, if an operator wants to fly an already NVIS-certified helicopter with different NVGs, it must conduct another certification program with the new NVGs.
The certification covers the installation of an NVIS, including internal and external aircraft lighting and third-generation NVGs. The latter can be either ITT F 4949 or Nogalight NL-93 models. Lighting should be NVG-compatible so as not to blind the pilot.
The NVIS’s lighting system should give adequate cockpit illumination for the naked eye, but it should not degrade the NVG performance. It must take into account the fact that pilots look outside through their goggles and look down to see the avionics. When they look back inside the cockpit after looking outside, they should not be blinded by light that is too strong.
“For years, we have designed cockpits that were NVG-capable, but they were not certified for commercial operations,” Bernd Osswald, a Eurocopter NVG integration specialist for the EC 145 in Donauwörth, Germany, told AIN. The joint preparation of an advisory circular (AC) involving the EASA, the FAA, TC and Eurocopter Deutschland changed the situation recently. “Some NVG manufacturers in the U.S. could apply for STCs whereas original equipment manufacturers could not apply for full NVIS approval,” Osswald said. He clarified that the current certification is for the hardware only. Operators have to apply to their national aviation authority for operating certification.
“The basic assumption for civil certification is that the NVGs are just an aid to night VFR flight,” the EASA expert added. As a result, helicopters with the NVG certification can be flown only in night conditions in which non-NVG operations are approved.
Operators interested in NVGs should keep in mind that NVGs do not morph night into day. They provide a field of view of only about 40 degrees. In addition, NVG wearers cannot see wires as far away as they can in daylight conditions.
According to the AC, instrument markings must be demonstrated during aided and unaided flight, and colors should be uniform to avoid confusion. For example, different shades of red in the cockpit are not accepted. Additionally, NVIS red with orange hue has not been accepted in cockpits equipped with amber caution lights/indicators.
Reflections should be carefully suppressed because NVGs might pick up even more reflections than unaided vision. Those reflections have to be blocked to prevent them from hindering the pilot’s vision while he is wearing NVGs.
The windshield should not decrease NVG light sensitivity by more than 12 percent. If the aircraft has an anti-ice function, the windshield should be tested with anti-ice on and off. Separately, emergency medical service (EMS) operations will require evaluation of cockpit protection from the passenger compartment if its lighting is not NVIS-compatible.
The certification test schedule should take into account moon cycles and sky condition. Starlight-only illumination is preferred, the AC recommends. “The adaptation of this military instrument to the civil world required appropriate testing on the ground and in flight,” the EASA expert told AIN. Flights are usually done first in the daytime. Then they are conducted at night with two pilots.
Single-pilot operations are allowed, but a second crewmember needs to wear NVGs for takeoff and landing, Osswald said. The second crewmember should assist in obstacle identification and clearance.
Eurocopter is currently trying to approve Northrop Grumman NVGs and is working on the same capability for other models. The EC 135 is scheduled to have its NVG capability certified in the third quarter of next year.