CONFLICT BETWEEN CONFIGURATION ELEMENTS
(a)Ensuring that there are no conflicts between the different configuration elements involves identifying any potential conflicts with previously embodied configuration elements prior to the embodiment of a new configuration element, such as a new modification or repair. This is necessary because the design approval holder, or declarant of a declaration of design for a particular modification or repair, cannot in all cases be expected to be aware of all the possible configuration elements embodied on all aircraft of a given type. In many cases, this verification may be limited to ensuring the absence of interfaces between configuration elements. For example, this may apply to repairs carried out in accordance with the SRM in areas where no other structural modifications or repairs are present. In addition, in some cases, the absence of conflicts may be ensured in cases in which a modification or repair has been specifically designed for an individual aircraft, taking into account its configuration during the design process. In concerns arise, and the person or organisation responsible for the continuing airworthiness of the aircraft is unable to determine the absence of conflicts affecting the airworthiness of the aircraft, assistance from an appropriately approved design organisation should be sought.
(b)The following list, although not exhaustive, provides examples of combinations of installations which have the potential to create compatibility issues; for example, the installation of:
— autopilots on aircraft with other modifications that alter flight characteristics, including the lift, drag, weight and thrust of aircraft. The cumulative effect of multiple modifications that individually increase drag should not be disregarded;
— multiple accessories mounted on the skid tubes of helicopters;
— changes to or the introduction of new operating limitations or procedures. This would include multiple flight manual supplements affecting the same or interconnecting systems;
— multiple modifications to the same structure (the superposition of stresses, changes in stiffness, or changes to safe life, fail safe, or damage tolerance characteristics should be considered);
— any software changes in interdependent systems;
— modifications to light-emitting or reflecting characteristics (internal and/or external) of aircraft with night vision imaging system (NVIS) lighting systems;
— automatic dependent surveillance-broadcast (ADS-B) Out equipment with previously installed GPS antennas or upgrades of global positioning system (GPS) antennas/navigators that may affect ADS-B Out function (performance);
— highly integrated avionics components (e.g.,one multi-function display (MFD) and one primary-function display (PFD) in cases in which interconnectivity was changed, added or removed);
— modifications to items that affect ditching certification (e.g. replacement windows with different construction or push-out window STCs, changes to waterline location, or the installation or relocation of equipment, such as valves, below the waterline);
— Equipment whose use under normal operation could damage other equipment in close proximity (e.g. heat from a searchlight mounted next to skid-mounted float bags on helicopters);
— any modification near attitude and heading reference system (AHRS) magnetic field sensors (flux valves, etc.);
— multiple modifications to the same primary structure that include the use of blind fasteners;
— multiple changes affecting ice protection system operation;
— de-icing boots with structural changes that could impinge on the ability of the boots to expand;
— multiple changes to the interior aircraft configuration (seats, emergency lighting, etc.) which may affect emergency evacuation of occupants and occupant protection;
— multiple modifications installing equipment that applies electrical loads on the same aircraft electrical generating system; or
— multiple modifications installing equipment that requires an assessment of electromagnetic compatibility.