41.—(1) A national permit to fly ceases to be in force if—
(a)the CAA has issued a directive that requires—
(i)an inspection to be carried out for the purpose of ascertaining whether the aircraft remains airworthy; or
(ii)modification or maintenance of the aircraft or any of its equipment necessary for the airworthiness of the aircraft for the purpose of ensuring that the aircraft remains airworthy; or
(b)completion of an inspection, modification or maintenance of the aircraft is required as a condition of the permit to fly.
(2) A national permit to fly which has ceased to be in force under paragraph (1) comes into force again as soon as—
(a)any such inspection, modification or maintenance has been satisfactorily completed; and
(b)in the case of an inspection, any consequential repair, replacement or modification has been satisfactorily carried out.
(3) A national permit to fly ceases to be in force—
(a)if any condition (other than a condition of the permit requiring an inspection, modification or maintenance) is not complied with;
(b)if the aircraft, engines or propellers, or such of its equipment as is necessary for the airworthiness of the aircraft, are modified or repaired, unless the repair or modification has been approved by the CAA or by a person approved by the CAA for that purpose.
(4) A national permit to fly is not in force unless the permit includes a current certificate of validity issued by the CAA or by a person approved by the CAA for that purpose.
(5) In this article “certificate of validity” means a certificate which certifies that a national permit to fly remains valid for the period specified in the certificate and a certificate of validity is current during that period.