In an effort to conserve cash, financially ailing US Airways Group Inc. said yesterday that it plans to ask the Internal Revenue Service for permission to delay payments into the pension plans of two of its employee groups.

The Arlington airline said it would ask the IRS for permission to spread out $67.5 million in payments into its flight attendants' and mechanics' 2004 pension plans over five years. The payments are due over the next 18 months.

"Rescheduling these payments will help US Airways to conserve its cash so that we have sufficient liquidity to operate the airline," Jerold A. Glass, US Airways vice president of employee relations, said in a statement.

The airline said the proposed payment rescheduling would not affect retirees or employees' ability to retire under the plans.

Randy Clerihue, a spokesman for the Pension Benefit Guaranty Corp., said that for the IRS to agree to such a request, the airline must make available appropriate collateral. The IRS and the PBGC, the federal agency that monitors corporate pension plans, would decide on the type of collateral US Airways should offer, Clerihue said. After US Airways submits its request, a decision would take at least a month, he said.

Such requests of the IRS are not uncommon. Last year, Northwest Airlines Corp. won approval from the tax agency to stretch out payments of $454 million into its pension plan for its salaried and contract employees over five years.

US Airways is scrambling to avoid a second bankruptcy filing as it seeks to secure $800 million in pay and benefit concessions from its employees before the end of September. The carrier must meet certain financial requirements by that time under the terms of its federally backed guarantee on $900 million in loans. It emerged from bankruptcy in March 2003.

Last week a report issued by Glanzer & Co., an independent financial adviser hired by US Airways' pilots union, said the airline could file for bankruptcy as early as next month and could even face liquidation if it failed to reach new cost-cutting agreements with its unions.

Analyst Raymond Neidl of Blaylock & Partners said US Airways' decision to seek additional time to pay into its pension plans was a signal that the carrier was trying to find ways to preserve cash to continue operating if it goes back into bankruptcy.

In addition to its current pension payments, the airline has a $130 million pension payment for 2003 due next month.

Battling its own pension woes, United Airlines said this summer that it would stop contributions to its employee pension plan until it emerged from bankruptcy.

Joe Tiberi, a spokesman for US Airways mechanics, said the union's attorneys were reviewing the airline's IRS request. Tiberi said union officials did not see any reason to be alarmed.