There were extensive problems encountered in operational and maintenance due to the large number of pre-mature failures of engines, components, and systems. Of the total of 189 engines in service, 139 engines (74%) failed pre-maturely and had been withdraw from service by July 1992, thus effectively shutting down operations. 62 of these engines had not even accomplished 50% of their 300 hours first overhaul point. Thus the desired serviceability showed a steadily decreasing trend.
Engineering reports mainly attribute RD-33 failures to design/material deficiencies causing discolored engine oil (8), cracks in the nozzle guide vanes (31), and surprisingly, foreign object damage (FOD). The eight material deficient engines (discolored oil) were repaired by the contractor under warrantee provisions, but the engines had to be recycled to the manufacturer. The thirty-one engines with cracks in their nozzle guide vanes were fixed in the field by contractor teams and adjustments were made to the entire engine fleet. But even though the incidents reduced the occurrences of the cracks, they continued.
But the FOD situation is the most interesting, especially after the inlet FOD doors received world press coverage, but there were other concerns about production quality control that led to problems.
Since the Indian Air Force received early model Fulcrum A's, some just after the 200th production article, there were quality control deficiencies that resulted in numerous pieces of FOD (foreign object damage) and tools being left behind after final construction inside of the aircraft. Remember that the Fulcrum skeleton is made first and then the skin is riveted over top, in the way aircraft were made in the fifties and sixties in the West. Nuts, bolts, tools, etc. all made their way to the engine bays and inlet ducts and when they were loosened up after accelerations they damaged engines and equipment.
On top of all this, it was discovered that the unique FOD doors on the MiG-29's inlets were not stopping material from getting into the engine ducts. Since the doors retracted "up" into the inlet, debris that was kicked up by the nose wheel lodged on or at the bottom of the door seal and then was ingested into the engine when the door opened during the nose gear lifted off the ground during takeoff.
This problem was known from the earliest days. After the first four MiG-29 prototypes were evaluated, the nose gear was moved further back, but nose wheel "mud-flaps" or guards were still required to protect the engine from flying debris. It took until 1988 before all delivered aircraft were so equipped, therefore the initial batch of InAF aircraft had to be locally retro-fitted with mud guards and that activity was not completed until June 1992. All costs were supposed to be re-imbursed by the contractor but Mikoyan reneged and left the InAF with $300,000 in liabilities. In subsequent MiG-29K/M models the FOD doors were replaced by screens that closed "down", forcing any debris out of the louvers repositioned to the lower side of the inlet duct..
The Indian Air Force procurement contract was concluded in September 1986, and the first engine was expected to go into overhaul in 1989. However, four engines prematurely came up for overhaul and no repair facility had been prepared. As time went on, 115 of the 122 engines (94%) prematurely failed and had to be re-cycled through engine depots in Russia at great cost. Backlogs were created and only 79 (65%) engines returned on schedule. Even when a regional Indian repair facility was completed in August 1994, the high failure rates continued and the majority of broken engines had to be sent back to Russian depots. Self-sufficiency was achieved in 1994, only after the operations tempo was significantly reduced on a permanent basis. In the process of refurbishing failed engines, the total technical life of most of the engine fleet was effectively reduced from 800 hours / 8 years to 400 hours / 4 years, at a minimum.
Non-availability of radar and weapon system components also resulted in the grounding of seven aircraft for a period of six to twenty months. Two may have been damaged for life due to cannibalization. Besides this, a large number of subsystems and computers experienced unpredicted failures in the last four years which adversely effected the operational readiness of the squadrons. Some of the computers were field-repaired by specialists from the manufacturers, others were replaced. These repair costs were all in excess to the initial contract costs. It was noted that the 10 additional computers, which were imported, cost the InAF around $806,000. Two Flight Data Ground Processing Units quickly became unserviceable during their warranty period and have been lying un-utilized and un-repaired for over two years.
The InAF Headquarters also noted in March 1991 report that a severe shortage of product support equipment had resulted in the decline of fleet availability by 15-20%, which in turn, took negative effect on operational readiness and mission requirements.