Every firehouse has its comedian, a firefighter who lightens the mood. For Station 51, the Los Angeles County Fire Department house seen in the pioneering procedural Emergency! that class clown was Chester "Chet" Kelly. Played by Tim Donnelly, Chet brought levity to the rescue series, playing practical jokes and wisecracking with his colleagues. Particularly John Cage.

With his antics and mustache, Donnelly was a memorable supporting actor on Emergency! Jack Webb, creator-producer of the series, was particularly fond of the California native. One of Donnelly's earliest roles sticks in the memory of Sixties television fans. In the Dragnet episode "The Big High," a preachy plot about the perils of pot, Donnelly played Paul Shipley, a father who enjoys a toke, leading to the death of his young infant in the bathtub.

Donnelly would appear in four more episodes of the 1967 Dragnet reboot, and turned up in Webb's Adam-12 a couple of times, before finding a steady home in Station 51. His Chet Kelly appeared in 122 episodes of Emergency! — nearly as many as the principal stars.

The series meant a lot to those in emergency medical services — and even helped to propagate paramedic services across America. This is why news of Donnelly's death came not from Hollywood trade publications but rather from the Los Angeles County Fire Museum.

The LACFM wrote on Facebook: 

"We at the Fire Museum are heartbroken as we sure all of you will be as well regarding the following news. It is with deep sadness that we announce the sudden passing of our friend, Tim Donnelly, this weekend. Tim, as you know, played Chet Kelly on the show Emergency! among many other roles during his acting career. To all the Emergency! fans, we want you to know that he was very excited about coming to the Museum in January for the 50th Anniversary. Many of the Museum Board Members have great memories of Tim from our time on Project 51 and personal contact."

Following Emergency!, Donnelly found small guest roles on CHiPs and Vega$, but his television credits ended in 1984 with a spot on The A-Team.

His brother, Dennis Donnelly, was a longtime TV director, helming 18 episodes of Emergency! and teaming with Tim on some installments of Project UFO.

Donnelly passed away on September 19. He was 77.