Copyright 1986 The New York Times Company
The New York Times
February 19, 1986, Wednesday, Late City Final Edition
SECTION: Section A; Page 1, Column 6; National Desk
LENGTH: 1209 words


BYLINE: By DAVID E. SANGER, Special to the New York Times


The top Morton Thiokol engineer present at the Kennedy Space Center before the Jan. 28 liftoff of the space shuttle Challenger said tonight that he had argued for hours with space agency officials not to launch the craft because of low temperatures.

He said that he persisted even after his own superiors had overruled him and given the agency a go-ahead.

The engineer, Allan J. McDonald, a 26-year veteran of Morton Thiokol Inc., which made the solid-fuel booster rockets for the shuttle, said that at a closed session last Friday before the Presidential panel investigating the explosion he recounted his ''somewhat heated'' exchanges with officials of the space agency. Notes to Commission

He said in a telephone interview tonight that those exchanges centered on the rocket seals that have become a major suspect in the explosion that killed the shuttle's seven crew members.

Mr. McDonald, who is the director of Thiokol's solid-fuel rocket motor project, also said he turned over to the commission detailed notes made in the course of his dispute with the officials of the National Aeronautics and Space Administration.

He said he first warned NASA officials about potential dangers after calculations performed by Morton Thiokol engineers in Utah showed that the temperature of the O rings, which seal joints in the booster rockets, was about 30 degrees Fahrenheit. That is about 23 degrees lower, he said, than the temperature of the rings in a January 1985 shuttle launching that resulted in the largest amount of ring erosion ever seen by NASA officials.

Seals Suspected in Disaster

The O rings are the leading suspect in the apparent failure of the right-hand solid-fuel booster rocket. It is now believed that they may have set off events that led to the fireball that consumed the Challenger.

In testimony before a Senate subcommittee today, Jesse W. Moore, the space agency's top shuttle official, said he was not told about low temperature readings on one of the rockets the morning of the launching and would have asked more probing questions had the issue been brought to his attention. [Page B9.]

Mark Weinberg, a spokesman for the Presidential commission, said, ''It would not be appropriate'' to say whether Mr. McDonald had appeared before the commission in its closed session at the Kennedy Space Center last week. Mr. McDonald said it was likely he would be called to appear at an open hearing of the commission next week. The commision has confirmed that it took testimony from several Morton Thiokol officials on Friday.

NASA officials said today that technical crews on the launching pad, using infrared sensors, had measured temperatures as low as 7 to 9 degrees Fahrenheit on the surface of the right-hand booster rocket, near the O ring seals that are suspected of failing.

A breach of the O rings would allow superhot gases to escape through the side casing of the 149-foot-long rocket, an event that NASA officials had previously considered unlikely, although some NASA engineers had warned more than a year ago that such a breach could be catastrophic.

Mr. McDonald said today that on the night of Jan. 27 he was arguing primarily with Lawrence B. Mulloy, who heads NASA's solid-fuel booster rocket project at the Marshall Space Flight Center in Huntsville, Ala.

''It was a very prolonged discussion, Mr. McDonald added. ''The engineers in Utah were largely in agreement with me.''

Nonetheless, he said, his superior, Joseph Kilminster, overruled his objections around 11:30 P.M. and transmitted to NASA a copy of a letter approving the launch. But Mr. McDonald said he believed the situation was so serious that he continued arguing his point even after the letter had arrived at Cape Canaveral.

''I argued before and I argued after,'' he said by telephone from his home in Ogden, Utah. ''The low temperatures make the O ring seals much harder, stiffer, and it caused them to shrink. It is hard to quantify, but qualitatively that is what happened.''

Mr. Mulloy did not return a message last night left on an answering machine at his home in Huntsville. There was no answer at Mr. Kilminster's home in Utah.

Mr. Mulloy has testified before the commission on the effects of the cold on the O rings. Mr. Kilminster has not, but his name has been mentioned before the commission in discussions about Morton Thiokol's agreement to go ahead with the launching.

Testimony Before Panel

In testimony before an open session of the Presidential commission last week, Mr. Mulloy, confronted with an impromptu test of the resiliency of the O rings by a panel member, Richard P. Feynman, said tests indicated that the rings lost resiliency as the temperature dropped toward 50 degrees Fahrenheit. But he added that specifications indicated they could operate safely down to 30 degrees below zero.

In his testimony Feb. 11, Mr. Mulloy said that data presented on the night before the launching by Morton Thiokol indicated that the resilience of the seal drops even further at temperatures of 20 or 25 degrees Fahrenheit. However, Mr. Mulloy said that ''under the conditions that we would see on launch day, given the configuration that we ran, that the seal would function at that temperature. That was the final judgment.''

He added, ''Ah, there were data presented as we have discussed, by some, by Thiokol engineering, that there was a suggestion that possibly the seal shouldn't be operated below any temperature that it had been operated on previous flights.''

Mr. Mulloy also said last week that Morton Thiokol had originally recommended against launching but reversed that position later the evening of Jan. 27.

At NASA headquarters tonight, Charles Redmond 3d, a spokesman, said, ''Clearly, the Morton Thiokol engineer has a point of view he is allowed to make, but beyond that I don't think we have any comment.''

At least some of Mr. McDonald's comments today appeared to contradict Mr. Mulloy's statements last week concerning the relationship between the cold and erosion of the O rings in previous launchings.

Last Wednesday, at a news conference, Mr. Mulloy was asked about the decision to launch despite the cold. ''What we went on,'' he said, ''was the basis of the data that we had that indicated that there was no direct correlation between the erosion and blowby on the primary ring and temperature, based on the previous flight data.''

''Blowby'' refers to a rush of gases past a seal.

But Mr. McDonald said today,''That is not quite correct.''

"Not a Strong Correlation"

''There is not a strong correlation,'' he said. ''But there is evidence that things got worse with low temperature.'' Before the Challenger launching, he said, the O ring was particularly cold because it had sat, uninsulated, in below-freezing temperatures the night before the launching.

Mr. McDonald, who is 48 years old and holds a bachelor's degree in chemical engineering from Montana State University and a master's degree in engineering administration from the University of Utah, said tonight that he was uncertain why his recommendation against the launching had been overruled.

''They felt, I am sure, that the basis for the concern was not fully conclusive,'' Mr. McDonald said.