---
kind: "section"
citation: "14 C.F.R. § 36.9"
title: "14"
number: "36.9"
heading: "Acoustical change: Propeller-driven small airplanes and propeller-driven commuter category airplanes."
url: "https://uscodex.org/cfr/14/36.9"
---

# §36.9. Acoustical change: Propeller-driven small airplanes and propeller-driven commuter category airplanes.


For propeller-driven small airplanes in the primary, normal, utility, acrobatic, transport, and restricted categories and for propeller-driven, commuter category airplanes for which an acoustical change approval is applied for under [§ 21.93(b)](/cfr/14/21.93.md?p=b) of this chapter after January 1, 1975, the following apply:

- (a) If the airplane was type certificated under this part prior to a change in type design, it may not subsequently exceed the noise limits specified in [§ 36.501](/cfr/14/36.501.md) of this part.
- (b) If the airplane was not type certificated under this part prior to a change in type design, it may not exceed the higher of the two following values:
  - (1) The noise limit specified in [§ 36.501](/cfr/14/36.501.md) of this part, or
  - (2) The noise level created prior to the change in type design, measured and corrected as prescribed in [§ 36.501](/cfr/14/36.501.md) of this part.

## Notes

### Amendments

[Amdt. 36-16, 53 FR 47400, Nov. 22, 1988; 53 FR 50157, Dec. 13, 1988; Amdt. 36-19, 57 FR 41369, Sept. 9, 1992]

### Authority

Authority: 42 U.S.C. 4321 et seq.; 49 U.S.C. 106(f), 40113, 44701-44702, 44704, 44715; sec. 305, Pub. L. 96-193, 94 Stat. 50, 57; E.O.11514, 35 FR 4247, 3 CFR, 1966-1970 Comp., p. 902.

### Source

Source: Docket No. 9337, 34 FR 18364, Nov. 18, 1969, unless otherwise noted.

### Amendments

[Amdt. 36-16, 53 FR 47400, Nov. 22, 1988; 53 FR 50157, Dec. 13, 1988; Amdt. 36-19, 57 FR 41369, Sept. 9, 1992]