14 CFR § 25.363 - Side load on engine and auxiliary power unit mounts.
---
identifier: "/us/cfr/t14/s25.363"
source: "ecfr"
legal_status: "authoritative_unofficial"
title: "14 CFR § 25.363 - Side load on engine and auxiliary power unit mounts."
title_number: 14
title_name: "Aeronautics and Space"
section_number: "25.363"
section_name: "Side load on engine and auxiliary power unit mounts."
chapter_name: "FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION"
subchapter_number: "C"
subchapter_name: "AIRCRAFT"
part_number: "25"
part_name: "AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES"
positive_law: false
currency: "2026-04-05"
last_updated: "2026-04-05"
format_version: "1.1.0"
generator: "[email protected]"
authority: "49 U.S.C. 106(f), 106(g), 40113, 44701, 44702 and 44704; Pub. L. 115-254, 132 Stat 3281 (49 U.S.C. 44903 note)."
regulatory_source: "Docket No. 5066, 29 FR 18291, Dec. 24, 1964, unless otherwise noted."
cfr_part: "25"
---
# 25.363 Side load on engine and auxiliary power unit mounts.
(a) Each engine and auxiliary power unit mount and its supporting structure must be designed for a limit load factor in lateral direction, for the side load on the engine and auxiliary power unit mount, at least equal to the maximum load factor obtained in the yawing conditions but not less than—
(1) 1.33; or
(2) One-third of the limit load factor for flight condition A as prescribed in § 25.333(b).
(b) The side load prescribed in paragraph (a) of this section may be assumed to be independent of other flight conditions.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as amended by Amdt. 25-23, 35 FR 5672, Apr. 8, 1970; Amdt. 25-91, 62 FR 40704, July 29, 1997]