Section 20"33 is amended to read as follows: 20.33 DURATION. A pilot certificate shall be of 60 day's duration and, unless the holder thereof is otherwise notified by the Administrator within such period, shall continue in effect indefinitely thereafter, unless sus pended or revoked, except that it shall immediately expire (l) at the end of each designated period 7/ after the date of issuance thereof if the holder of such certificate fails to secure an endorsement by an authorized inspector or,

more »

... in case of a student..pilot., certificate, a medical examiner* of the Administrator within the last 45 days of each such period, or (2) at any time an authorized inspector of the Administrator^ or, in case of a student pilot certificate, an authorized inspector or medical examiner of the Admird-stratcr* shall refuse to endorse such certificate after inspection or examination: Provided, That no solo or limited-commercial pilot certificate shall be endorsed to remain effective beyond May 1, 1941, in the case of solo certificates, or May 1, 1942, in the case of limited-commercial certif icates* The duration or endorsement period of any pilot certificate expiring on or after November 29, 1940, which has been suspended at any time during such duration or endorsement period, is extended by the length of time of such suspension.