Service Bulletin No. 669
Hartzell Engine Tech (HET) Exhaust Bypass Valve Assembly
Publications
Service Bulletin No. 669
DATE RELEASED:
June 29, 2026
SUBJECT:
Hartzell Engine Tech (HET) Exhaust Bypass Valve Assembly
MODELS AFFECTED:
TEO-540-C1A engines with HET P/N 47E31569
TIME OF COMPLIANCE:
When Manifold Absolute Pressures are Instable
