How do Service Bulletins (SBs) differ from Airworthiness Directives (ADs)?

How do Service Bulletins (SBs) differ from Airworthiness Directives (ADs)?

• A. ADs are legally enforceable safety directives; SBs are manufacturer recommendations, some of which may be made mandatory by ADs or FAA action.
• B. SBs are legally enforceable; ADs are merely recommendations.
• C. SBs apply only to military aircraft; ADs apply to civilian.
• D. SBs and ADs are the same.

Answer: (A)

The main point is about enforceability and authority. Service Bulletins are issued by manufacturers as recommendations for inspections, inspections, or modifications to address a potential or known issue. They’re not legally binding by themselves. Airworthiness Directives, on the other hand, come from the FAA and are legally enforceable requirements that must be followed to maintain airworthiness. Why this answer fits best is that it captures the key distinction: ADs compel action to correct an unsafe condition, while SBs are advisory unless the FAA or an AD later mandates them. It’s also possible for an SB to be made mandatory if the FAA incorporates it into an AD or otherwise requires compliance, but by itself an SB does not carry the force of law. In short, SBs are manufacturer recommendations; ADs are legally enforceable directives from the FAA.

The main point is about enforceability and authority. Service Bulletins are issued by manufacturers as recommendations for inspections, inspections, or modifications to address a potential or known issue. They’re not legally binding by themselves. Airworthiness Directives, on the other hand, come from the FAA and are legally enforceable requirements that must be followed to maintain airworthiness.

Why this answer fits best is that it captures the key distinction: ADs compel action to correct an unsafe condition, while SBs are advisory unless the FAA or an AD later mandates them. It’s also possible for an SB to be made mandatory if the FAA incorporates it into an AD or otherwise requires compliance, but by itself an SB does not carry the force of law.

In short, SBs are manufacturer recommendations; ADs are legally enforceable directives from the FAA.