THE REPUBLIC OF Singapore Air Force (RSAF) Northrop F-5E/F upgrade programme has been given a production go-ahead, following the resolution of major avionics-integration problems.

Prime contractor Singapore Technologies Aerospace (STAe) says that work will begin immediately on the upgrade to the newly designated F-5S/T standard. The total number involved has not been released, but the upgrade is thought to cover about 40 aircraft.

The upgrade was originally launched in 1989, as a follow-on to STAe's avionics upgrade and re-engineing of the RSAF's McDonnell Douglas A-4 fleet. Two years of flight-testing began in 1994, using a modified F-5S and tandem-seat F-5T.

The Singaporean F-5 upgrade had until recently been plagued by major avionics-integration problems, and is now thought to be running at least two years behind its original schedule.

The problems focused primarily on the replacement of the F-5's outdated Emerson APQ-159 system with the Fiar Grifo F multi-mode pulse-Doppler radar. Other integration problems included the fitting of a new GEC-Marconi head-up display.

Only after, the RSAF gave integrator Elbit Computers of Israel an ultimatum, and threatened to drop the Grifo in favour of an alternative radar, were the problems finally resolved. Remedial measures included pushing back the F-5's forward bulkhead, fitting a nose plug and removing one of its two 20mm cannons.

The F-5S/T will be equipped, with the Litton IN-93 laser inertial-navigation system, Elisra SPS-2000 radar warning receiver, twin head-down multi-function displays and hands-on throttle and stick controls.

Source: Flight International