Federal safety investigators Wednesday urged the Federal Aviation Administration to require the immediate inspection of all DC-9 jets to determine if any rear exit handles are broken or cracked. The recommendation stems from a Dec. 3 collision in Detroit that killed eight.

The National Transportation Safety Board said it was "concerned that extensive wear of (the) handle shaft" could cause the handle on a tailcone evacuation exit to jam.The investigation of the collision of two Northwest passenger jets at Detroit Metropolitan Airport indicates some of the eight fatalities aboard the DC-9 may have resulted when a rear emergency evacuation handle jammed, the board said.

In such a situation, the board said, excessive force could be applied that could break the handle shaft, rendering the emergency evacuation exit on the tailcone assembly of the DC-9 inoperable.

The safety board said the FAA should require an immediate visual examination of interior and exterior tailcone release handles for broken or cracked shafts and other damage.

Any damage should be immediately repaired, the safety board said.

While the board's recommendation is not binding, it carries considerable weight. The board investigates all transportation accidents involving U.S. carriers.

A spokesman for the FAA said the recommendation was under study.

The board also recommended the FAA immediately require that:

-The McDonnell-Douglas Aircraft Co., manufacturer of the DC-9, redesign the aircraft's tailcone release mechanism "to correct its propensity for damage and malfunction."

-DC-9 tailcone maintenance manuals be revised to include procedures for visually examining tailcone release handles for damaged shafts.

-That DC-9 operators include "hands-on" training regarding the tailcone release system for flight crews and flight attendants.

-Require periodic inspections of DC-9 tailcones and release handles.

In a letter to FAA administrator James B. Busey, the safety board said its investigators found two of the eight victims, one a flight attendant, inside the DC-9's tailcone near the evacuation slide.