FAR 21.700 — Lavatory Oxygen Systems
FAR 21.700 applies SFAR No. 111 lavatory oxygen system requirements (§121.1500) to Part 21 certification. What pilot students need to know.
In Plain English
FAR 21.700 is a short cross-reference rule. It states that the requirements of § 121.1500 — known as SFAR No. 111, Lavatory Oxygen Systems — also apply to Part 21.
In plain terms:
- Part 21 covers the certification procedures for aircraft products and parts (type certificates, production approvals, airworthiness certificates, etc.).
- SFAR 111 is a Special Federal Aviation Regulation that imposes safety requirements on chemical oxygen generators installed in aircraft lavatories, originally issued in response to security concerns about lavatory oxygen systems being used to start fires.
- By incorporating § 121.1500 into Part 21, the FAA ensures that manufacturers and certification applicants — not just air carriers operating under Part 121 — must comply with the lavatory oxygen system requirements during the design, production, and certification process.
Why it matters operationally: While line pilots rarely interact with this rule directly, it explains why many transport-category aircraft have disabled or modified lavatory oxygen systems. As a pilot, you should know the lavatories may not have functional supplemental oxygen, and brief passengers and cabin crew accordingly.
Regulation Text
14 CFR § 21.700§ 21.700 SFAR No. 111—Lavatory Oxygen Systems.
The requirements of § 121.1500 of this chapter also apply to this part.
Oral Exam Questions a DPE Might Ask
Q1What does FAR 21.700 require?
Per **FAR 21.700**, the requirements of § 121.1500 — SFAR No. 111, Lavatory Oxygen Systems — also apply to Part 21, extending those lavatory oxygen rules to the certification process.
Q2Why would a Part 21 certification rule reference a Part 121 operating rule?
**FAR 21.700** incorporates § 121.1500 so that lavatory oxygen system requirements apply during aircraft design, production, and airworthiness certification under Part 21, not just to Part 121 air carriers.
Q3What is SFAR No. 111 and where is it found in the regulations?
SFAR No. 111 is the special rule governing lavatory oxygen systems, codified at § 121.1500, and **FAR 21.700** makes its requirements applicable to Part 21 as well.
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Related Sections in Part 21