Airworthiness of Aircraft — Page 64, Lesson 107

Let's pick up with the continuing airworthiness side of things. I want to walk you through what happens after an aircraft gets its Certificate of Airworthiness — how it stays legal to fly, and who is responsible for what. First, Continuing Airworthiness. This is the ongoing obligation to keep the aircraft in a condition where it's still safe to fly. The State of Registry — that's the country where the aircraft is registered — is responsible for determining if an aircraft continues to be airworthy. So it's not a one-time check at delivery; it's a continuous duty. And here's a specific requirement: that state must maintain a system for recording faults, malfunctions, defects, or other occurrences which might affect the airworthiness of aircraft with a maximum take-off mass greater than 5700 kg. So for heavier aircraft, there's a mandatory reporting and recording system for anything that could compromise airworthiness. Next, Structural Integrity / Corrosion Control. This shifts responsibility to the State of Design — the country that originally certified the aircraft type. That state is required to ensure that a structural integrity programme exists, again for aircraft with a maximum take-off mass greater than 5700 kg. The purpose is to make sure the airframe stays sound throughout its life. And the programme must include information concerning corrosion control — because corrosion is a slow, silent threat to structural strength, and it has to be actively managed. Now, Validity of the C of A. The Certificate of Airworthiness will be renewed, or will remain valid, provided that the continued airworthiness of the aircraft has been determined by a periodic inspection. The period between those inspections is established by the state — so the state sets the inspection interval. Now here's the damage scenario: if an aircraft is damaged, it's the responsibility of the State of Registry to judge whether the damage is of such a nature that the aircraft is no longer airworthy. So the registry state makes that call. And if the damaged aircraft is repaired, the State of Registry is to specify the necessary repairs, and to determine that such repairs have been properly carried out — before re-issuing a C of A. So the repair work is prescribed and verified by the registry state, and only then does the certificate come back. Next, Aircraft Limitations and Information. Each aircraft is required to have a flight manual — or other means — in which the approved limitations are defined, and additional information is contained that's necessary for the safe operation of the aeroplane. So the flight manual is the authoritative source for what the aircraft can and cannot do. And here's a specific detail: where the determined limiting speeds are specified as a Mach number, the aircraft is to be fitted with a Mach meter. So if the limiting speed is expressed in Mach — which is the ratio of true airspeed to the speed of sound — then the cockpit must have an instrument that displays Mach number. Finally, Information. When a Contracting State first enters an aircraft on its register, and issues or validates a Certificate of Airworthiness, it shall inform the State of Design that it has done so. So the registry state must notify the design state when a new aircraft is registered and certificated. That keeps the design state aware of where its aircraft are operating. So the key split to remember: the State of Registry handles continuing airworthiness, damage judgment, and repairs. The State of Design handles the structural integrity programme and corrosion control. And the flight manual carries the approved limitations, with a Mach meter required if speeds are given in Mach.