The overwhelming electoral success last month by incumbent Mayor Raymond L. Flynn in Boston's predominately Black sections indicates that the white Irishman has managed to build a citywide coaltion.

Political observers said the ability of Flynn into reach out into minority communities represented the first time a politician of Irish-ancestry has managed to attract substantial Black support.

Primarily Black sections of Boston, such as Dorchester and Roxbury, demonstrated overwhelming confidence for Flynn in the September 22 preliminary election to the tune of 90% of the popular vote. Flynn won bigger in the predominantly Black wards of these districts than in his own home ward.

In 1983, when Flynn first ran for office, his principal opponent was Melvin H. King, a Black politician from South Boston. This time his opponent, city Councilor Joseph Tierney, was much less formidable, especially in these Black areas.

None of the councilors in these wards seemed absolutely satisfied with Flynn. But many constituents and politicians said they have seen marked progress by Flynn on minority issues.

Councilor Charles Yancey of the Dorchester and Mattapan section of Boston said the two key issues for minorities are housing and public safety and that the incumbent mayor has focused city resources into less urgent problems.

Yancey said a "combat zone" mentality in Boston allows public safety to be ignored in certain areas. "Criminal activity is allowed to continue provided it does not leak out into the white community," said Yancey.

"It has been like pulling teeth trying to get support from the mayor and police in these areas," said Yancey.

Councilor James E. Burn of the Roxbury section of Boston said Tierney's campaign has remained low key on all of the issues pertinent to the Black sections of Boston. He said Flynn's major success has been in the issue of housing.

Evelyn Friedman, a spokesman of the Tierney Election Committee, said that the challenger's main concerns are those of housing and public schools.

"We want to create affordable housing but not have people at each others' throats," said Friedman.

Burn and Daniel Burke, Secretary of the Treasury of Boston's School Board and teacher in the Roxbury school district, feel that education is the third key issue for these areas. Burke said Flynn's success among his Black constituency is in part due to the appointment of Laval Wilson, who is the first Black superintendent of Boston schools.

"He is the most powerful superintendent of schools in the nation," said Burke.

But Yancey said not all of Flynn's actions this past term have benefitted Blacks in Boston. "Flynn has not been aggressive in hiring people of color to high-paying city positions," said Yancey.