---
kind: "section"
citation: "14 C.F.R. § 27.659"
title: "14"
number: "27.659"
heading: "Mass balance."
url: "https://uscodex.org/cfr/14/27.659"
---

# §27.659. Mass balance.

- (a) The rotors and blades must be mass balanced as necessary to—
  - (1) Prevent excessive vibration; and
  - (2) **Prevent flutter at any speed up to the maximum forward speed.**
- (b) The structural integrity of the mass balance installation must be substantiated.

## Notes

### Amendments

[Amdt. 27-2, 33 FR 963, Jan. 26, 1968]

### Authority

Authority: 49 U.S.C. 106(f), 106(g), 40113, 44701-44702, 44704.

### Source

Source: Docket No. 5074, 29 FR 15695, Nov. 24, 1964, unless otherwise noted.

### Amendments

[Amdt. 27-2, 33 FR 963, Jan. 26, 1968]