The U.S. aircraft register, updated daily
Approved modifications · supplemental type certificate · current · amended

SP830SO

Vibration approval for single engine tractor installation only, on P & W Model R1340-AN-1(S3H1 or S1H1 commercial designation engines. (12D 40/6101A-10S). Held by Metropolitan Propeller Repair, INC, which holds 5 approved modifications in all. Last revised February 20, 1976. System: propeller.

What it applies to

Kind of product
Propeller
Design holder
Hamilton Standard Division
Models
12D
Type certificate
P-257
The FAA's record
On the FAA's site

What an approved modification is

A supplemental type certificate is the FAA's approval of a change to a certified design: a new engine or propeller, avionics, an autopilot, floats, a parachute, a larger fuel tank, an ice-protection kit. The company holding it may sell the kit and the paperwork to owners of the listed models; the modification then becomes part of that aircraft's record. The FAA's list says what was approved and for which models, not how many aircraft carry it.

Source: FAA supplemental type certificates (Dynamic Regulatory System). Register counts from the FAA register of October 19, 2026.