The House Armed Services Committee will hold a hastily arranged hearing today on the military need for continued deployment of the aging force of Titan II missiles.

Following last Friday's explosion at the Damascus, Ark., Titan site that killed one airman and injured 21 more, several members of the House amd Senate, including Sens. Bob Dole (R-Kan) and David Pryor (D-Ark.), have called for a new look at whether the 18-year-old missiles should remain operational.

Called to appear before the committee are Air Force Secretary Hans Mark; the Air Force vice chief of staff, Gen. Robert C. Mathis, and Maj. Gen. Chris Adams, the Strategic Air Command's deputy chief of operations.

The Air Force officials are expected to defend retention of the 52 missiles now located at 54 Titan sites spread equally in Arkansas, Kansas and Arizona. The Damascus site and another at Rock, Kan., where a 1978 accident killed two airmen, are not operational.

The 52 missiles, with their nine-megation warheads, represent almost one-third the total megatonnage in the U.S. land-based ICBM force. The remainder is spread among the 1,000 far smaller but much more accurate Minuteman ICBMs.

Each Titan warhead has the power to destroy buildings in a normal city out to a radious of nine miles.

Since their introduction into the U.S. strategic force in 1963, the Titans have been targeted primarily on cities. They are far less accurate than any other U.S. missile, according to figures supplied to the Senate Foreign Relations Committee last year by former Deputy Defense Secretary Paul Nitze.

Last summer, the SAC commander, Gen. R. H. Elis, described the Titan as as "especially effective against an economic and industrial target base."

Such "soft" targets, according to Pentagon planners, would not be the first ones to be hit by U.S. ICBMs, particularly under President Carter's newly approved strategic doctrine, which calls for hitting military targets first.

The Titans thus would have to survive any Soviet first strike against the United States. The Air Force, however, has never increased the cement hardness of the Titan missile silos and they remain as they were in the mid-1960s, capable of withstanding only blast pressure created by an incoming Soviet warhead of 300 pounds per square inch. The Minute-man silos have twice been upgraded and now can withstand a blast of 2,000 pounds per square inch.

"The Titans," one Pentagon analyst said yesterday, would be "an easy target to hit and destroy."

Another area for questions will be the need to replace key Titan parts that are aging, and the lack of flight testing for the missile.

Secretary Mark, in a news conference, said the Damascus accident was the result of "human error." A three-pound wrench socket dropped from the third level to the seventh level of the 103-foot missile, bounced off a strut and punctured the missile's fuel tank.

An air Force report on the missile airframe, released earlier this year, noted that as of last year, 19 Titan II missiles have required one or more patches on their tanks to repair surface cracks.

Mark also referred to the reliability of liquid-fueled rockets, noting that the United States has continued to use them for its space program.

A committee source yesterday said Mark would be asked to compare the "controlled situations" that surround the launch of a rocket into space and the Titan situation where the rocket has been in a silo for about 18 years with only periodic complete overhauls every several years.

The reliability of the Titan will be another area for committee questions, according to the staff members.

When the Pentagon first announced in 1967 that it was planning to drop the Titan II, one reason given was the need for several test firings each year to ensure that the missiles, which were then only four years in operation, were "still in good working order," according to a news story at the time. Flight testing was stopped because there were no Titan missiles to replace those test fired.

Since 1969, however, there has not been regular testing of the Titan. The last actual launch of a Titan took place in 1976, when a new guidance system was used.

Nowadays, several Titans a year are taken from their silos and shipped to California where Aerojet-General Corp. fires up their engines in a static test.

In contrast, each year a dozen Minuteman missiles and a dozen submarine-launched missiles are flight tested to assure the reliability of the rocket engines and guidance systems.

Yesterday, a House-Senate conference committee approved language directing the Air Force secretary to "acquire and install" an "appropriate warning system" at each Titan II site located near a populated area.

The committee, in attaching its provision to the fiscal 1981 military construction authorization bill, left up to the Air Force the type of system to be installed.

The proposal for a Titan warning siren ironically was first introduced last year by Sen. Pryor as a direct result of an oxidizer leak at the Damascus site in 1978. The Air Force opposed it then and again this year on the grounds it was not necessary. Pryor got it through the Senate Sept. 16, three days before the Damascus missile blew up.

Lacking such a warning system, the Air Force and the local sheriff had to work through the night to tell residents within five miles of the site that they had to evacuate.