You want to look at the estimated time more then the annual failure rate. Here's an example:
Clairvaux class Light Carrier 14,000 tons 819 Crew 2044.4 BP TCS 280 TH 570 EM 540
4071 km/s Armour 3-51 Shields 18-400 Sensors 12/16/0/0 Damage Control Rating 4 PPV 0
Annual Failure Rate: 348% IFR: 4.8% Maint Capacity 411 MSP Max Repair 80 MSP Est Time: 1.24 Years
Hangar Deck Capacity 3000 tons Magazine 850
Matsumoto IE-M8 (19) Power 60 Fuel Use 80% Signature 30 Armour 0 Exp 5%
Fuel Capacity 1,000,000 Litres Range 160.7 billion km (456 days at full power)
Gamma R400/16 Shields (9) Total Fuel Cost 144 Litres per day
AGM-5A 'Lance' FTR Guided Missile (284) Speed: 20,400 km/s End: 9.2m Range: 11.3m km WH: 6 Size: 3 TH: 88 / 53 / 26
O/SPS-28 Search Sensor (1) GPS 5120 Range 45.8m km Resolution 80
O/SQR-22 Thermal Sensor (1) Sensitivity 12 Detect Sig Strength 1000: 12m km
O/SDR-20 Electromagnetic Sensor (1) Sensitivity 16 Detect Sig Strength 1000: 16m km
Strike Group
12x Crusade Fighter Speed: 8260 km/s Size: 4.6
Missile to hit chances are vs targets moving at 3000 km/s, 5000 km/s and 10,000 km/s
This design is classed as a Military Vessel for maintenance purposes
The ship is guaranteed to suffer some maintenance failures within a year, but it has enough maintenance supplies to last for a year and a half before things start going unfixed. Since I've never had to deploy my fleet for more then a month or two in this game, this is more then enough. Decide how long you'd like your ships to remain in space without an overhaul and tweak the engineering sections to match that.