MG 16  Certification guidance for rotorcraft Night Vision Imaging System (NVIS) aircraft lighting systems

This AMC provides further guidance and acceptable means of compliance to supplement FAA AC 27-1B Change 7 MG 16, which is the EASA acceptable means of compliance, as provided for in AMC 27 General. However, some aspects of the FAA AC are deemed by EASA to be at variance with EASA’s interpretation or its regulatory system. EASA’s interpretation of these aspects is described below. Paragraphs of FAA AC 27-1B Change 7 MG 16 that are not amended below are considered to be EASA acceptable means of compliance.

[...]

d.       References (use the current versions of the following references).

(1)      Regulatory (CS-27).

(2)     Other references

[...]

e.       Background.

[...]

(7)     Night vision goggles (NVGs) enhance a pilot’s night vision by amplifying certain energy frequencies. The NVGs for civil use are based on performance criteria in ETSO-C164 and RTCA Document DO-275. These NVGs are known as ‘Class B NVGs’ because they have filters applied to the objective lenses that block energy below the wavelength of 665 nanometres (nm). The Class B objective lens filter allows more use of colour in the cockpit, with truer reds and ambers. The ETSO specifies Class B NVGs for civil use. Because NVGs will amplify energy that is not within the range of the filter, it is important that the NVIS lighting system keeps those incompatible frequencies out of the cockpit. However, there are NVGs in civil use that do not conform to the ETSO-C164 standard because they have Class A filters on their objective lenses. Class A filters block energy below the wavelength of 625 nm. As a result, Class A NVGs amplify more wavelengths of visible light, so they require special care in the use of colour in the cockpit. Applicants are advised that Class A NVGs are deemed to be not acceptable for certification by EASA.

[...]

(9)      Point 21.A.91 of Annex I to Regulation (EU) No 748/2012 contains the criteria for the classification of changes to a type certificate. For NVIS-approved rotorcraft, experience has shown that some changes, which are classified as being minor according to the AMC to 21.A.91 for unaided flight, may have an appreciable effect on the cockpit/cabin lighting characteristics, and thus on crew vision through the NVGs. Therefore, the classification of design changes of NVIS-approved rotorcraft should take into account the effects on cockpit/cabin lighting characteristics and the NVIS.

[...]

f.       Procedures.

[...]

(6)      Required equipment, instrument arrangement and visibility.

(i)      In addition to the instruments and equipment required for flight at night, the following additional instruments and equipment will typically be necessary for NVG operations (to be defined for each rotorcraft). The applicable operational regulations that specify aircraft equipment required for night and NVG operations should be reviewed.

(A)     NVIS lighting.

(B)     A helmet with suitable NVG mount for each pilot and crew member required to use NVGs.

(C)     NVGs for each pilot and crew members required to use NVGs.

(D)     Point SPA.NVIS.110(b) of Annex V (Part-SPA) to Regulation (EU) 965/2012 on air operations, and the associated AMC and GM, requires a radio altimeter with an analogue representation. It is recommended that an applicant carries out a careful evaluation of the radio altimeter human-machine interface (including the presentation of height and the possibility of selecting the DH) to establish that it is able to provide the crew with the necessary information.

(E)     A slip/skid indicator.

(F)     A gyroscopic attitude indicator.

(G)     A gyroscopic direction indicator or its equivalent.

(H)     A vertical speed indicator or its equivalent.

(I)      Communications and navigation equipment necessary for the successful completion of an inadvertent IMC procedure in the intended area of operations.

(J)      Any other aircraft or personal equipment required for the operation (e.g. curtains, NVG stowage, extra batteries for NVGs).

[Amdt No: 27/6]