YAKOVLEV HAS ISSUED a service bulletin warning owners and would-be-purchasers of the Yak-52 light aircraft that some earlier models are not fully capable of aerobatics.

The Yak-52 is a radial-powered primary trainer, a tandem-seat version of the Yak-50 aerobatic aircraft. The type has been in production in Romania by Aerostar since 1975.

Yakovlev has broken down the Yak-52 production run into four groups. The first group, aircraft built before 1986, has load-factor limits of +5g and -3g and should not be used for aerobatic manoeuvres or intentional spins, the design bureau says.

The second group consists of Yak-52s built before 1986, which have had spar modifications, and can be flown to +7/-5g in so-called "sportsman"-type aerobatics.

The third group, of aircraft made from late 1986, has heavier spars and can be flown to +7/-5g in "intermediate" aerobatics.

The fourth consists of Yak-52s modiÌed with a spar strap, allowing them to be flown to +7/-5g in "advanced" aerobatics.

Source: Flight International