Aeroplane Equipment and Instruments — Page 86, Lesson 140

I want to walk you through the aeroplane equipment and instruments requirements that apply to commercial operations. Let's start with electrical circuit fusing. Most circuit protection systems on aeroplanes use circuit breakers rather than fuses. But where fuses are fitted, there must be a supply of replacement fuses available for use in flight — specifically for those fuses that can actually be replaced in flight. The regulation requires at least 10% of each type and fuse rating, with the important proviso that there are not less than 3 of each type and rating. So if you have a 5-amp fuse type, you need at least 3 spares, and if 10% of the total fitted would be fewer than 3, you still carry 3. Now, windshield wipers. These — or an equivalent means of clearing precipitation — are required at each pilot station if the maximum take-off mass, or MTOM, is greater than 5700 kilograms. Below that threshold, wipers aren't mandatory, though many aeroplanes still have them. Next, there's a list of items that do not require an equipment approval. That means you don't need a separate certification or approval from the authority to install or carry these items. The list includes: fuses, torches, time pieces, chart holders, first aid kits and emergency medical kits, megaphones, survival and pyrotechnic signalling equipment, and child restraint devices. These are considered standard equipment that doesn't need individual approval. Let's move to seats and harnesses. A seat or a berth must be provided for every person on board over the age of two. Each passenger seat must be equipped with a safety belt — that can be with or without a diagonal strap — or a safety harness. For infants, acceptable child restraint devices may be used. For flight crew — that includes each flight crew member seat and any seats alongside pilots' seats — the requirement is more stringent. Those seats must be fitted with a safety belt and a shoulder harness, together with a device to automatically restrain the occupant in the event of sudden deceleration. That automatic restraint device is typically an inertia reel that locks during rapid deceleration. Cabin crew seats must have safety belts with shoulder harnesses. However, additional cabin crew may use passenger seats, which only need a safety belt. All safety belts with shoulder harnesses must have a single point of release. That means one buckle or latch releases both the lap belt and the shoulder straps simultaneously, so you can exit quickly in an emergency. For aeroplanes with an MTOM of 5700 kilograms or less, instead of a full shoulder harness, crew seats can be fitted with belts with a diagonal shoulder strap — that's a single strap that goes across the chest from one shoulder to the opposite hip, rather than a full two-strap harness. For aeroplanes with an MTOM of 2730 kilograms or less, even the diagonal shoulder strap is not needed — just a lap belt is sufficient for crew seats. Finally, 'Fasten Seat Belts' and 'No Smoking' signs. Aeroplanes where the passenger seating is not visible from the flight deck must be fitted with signs to alert passengers and cabin crew when seat belts are to be fastened or when smoking is not permitted. These signs are typically illuminated placards controlled from the flight deck. If the flight crew can see all passenger seats directly, signs aren't mandatory, but they're still commonly fitted.