This Day in FAA History: May 25th

Full FAA Chronology at this link.
19610525: A Special Civil Air Regulation effective this date banned the use of portable FM radios on U.S. civil aircraft. Radios having oscillators operating within or very near the Very High Frequency (VHF) band affected the VHF radio navigation system of the aircraft.
19700525: FAA issued the first supplemental type certificate for installation and operation of area navigation equipment in general aviation aircraft to the Butler National Corporation for use of the Butler Vector Analog Computer. The certificate permitted the use of this equipment during the en route, terminal, and approach phases of operation. (See October 1, 1969.)
19780525: PATCO began intermittent slowdowns to protest the refusal of some U.S. flag carriers to provide controllers with overseas familiarization flights. The slowdowns lasted until May 26 and were renewed on June 6-7. Delays were especially severe because of the increased air travel resulting from new low transatlantic and domestic fares (see March 15, 1978, and June 21, 1978).
19790525: An American Airlines DC-10 crashed into an open field near Chicago’s O’Hare airport after its left engine and pylon assembly separated from the aircraft on takeoff. The engine and pylon rotated up and over the left wing, taking part of the wing’s leading edge with them and damaging the control system. The ensuing crash and fire killed all 272 persons aboard the flight and two people on the ground, an unprecedented toll for an airline accident within U.S. airspace.
Early in its investigation, the National Transportation Safety Board discovered the presence of a fatigue fracture of a pylon forward thrust link attach bolt. On May 28, FAA Administrator Langhorne Bond ordered all airlines to keep their DC-10s on the ground until they had completed certain visual inspections. The next day, after learning that these checks were turning up potentially dangerous deficiencies in the pylon mountings, Bond grounded the entire U.S. DC-10 fleet pending a more comprehensive inspection. His order included U.S.-certificated Airbus A-300s because of the similarity of their pylon to the DC-10’s.
As these inspections progressed, evidence mounted that the problem might lie in American Airline’s non-standard use of a forklift to dismount and remount engine and pylon as a single unit during maintenance. Similar cracks had been found on DC-10s operated by Continental Airlines, the only other carrier using the forklift method. On June 5, however, the discovery of cracks that appeared unrelated to the forklift procedure strengthened evidence that seemed to suggest the existence of some more fundamental problem. On June 6, Bond suspended the DC-10’s type certificate indefinitely. He then ordered three parallel investigations into the DC-10 issue.
Thirty-seven days later, FAA’s investigative teams concluded that the aircraft destroyed in Chicago had indeed been damaged by the forklift procedure. This was also the cause of the other cracks found in the pylons of DC-10s operated by American and Continental. (The two airlines later received civil penalties of $500,000 and $100,000 respectively for using the procedure.) Other findings of the teams supported the conclusion that the DC-10 should be returned to service, and FAA therefore lifted the grounding order. The agency required a stringent program of inspections, however, and directed the manufacturer to redesign certain engine mount components.
19930525: DOT announced a new U.S.-Russian aviation agreement, updating and expanding an accord signed in June 1990 (see entry for February 16, 1990). Under the pact, the U.S. obtained new rights to fly over parts of Russia to points in Asia, and Russia received rights to serve 11 new U.S. cities. (See June 17, 1992, and October 14, 1994.)
20000525: FAA issued final rules ordering operators of 719 Boeing MD-80, MD-88, MD-90, DC-10, and MD-11 aircraft to replace insulation blankets covered with metalized Mylar. The agency had proposed the rules in August 1999 to minimize the risk of fire spreading aboard these types of aircraft. The airworthiness directives required operators to determine whether their planes had metalized Mylar-covered insulation materials, if so to note where they were located, and to replace them with new insulation blankets within five years. Replacement materials had to meet FAA’s new flame propagation standard, which was based on an American Society for Testing and Materials flammability standard. (See August 11, 1999; September 8, 2000.)
20000525: FAA told air traffic controllers nationwide to review emergency procedures after a US Airways flight with a dying passenger was delayed in making an emergency landing in Baltimore, Maryland. A US Airways spokesman said the airline followed all on-board procedures, including the use of a heart defibrillator, and that three passengers who were nurses volunteered to help. Sources close to an investigation of the incident said that the 50-year-old woman did not respond to the emergency treatment, and that the delayed landing probably was not a factor in her death.
20180525: A three-judge panel of the DC Circuit Court of Appeals held that “the FAA can require an insulin-dependent diabetic to submit to expensive and invasive glucose-monitoring to establish that he is medically fit to fly commercial aircraft.” (See June 22, 2020.)
20210525: FAA announced Mexico did not meet International Civil Aviation Organization (ICAO) safety standards. Based on a reassessment of Mexico’s civil aviation authority, FAA downgraded Mexico’s rating to Category 2. While the new rating allowed Mexican air carriers to continue existing service to the United States, it prohibited any new service and routes. U.S. airlines no longer were allowed to market and sell tickets with their names and designator codes on Mexican-operated flights.