# AD 51-23-03: Battery Box Insulation

- Type: Airworthiness directive
- Status: Current
- Products: Piper PA-16, PA-20 and PA-22
- Published: December 4, 1956
- Issued: December 4, 1956
- Superseded by: Nothing supersedes this AD
- Product type: Aircraft, Small airplane
- Registered aircraft: 829 may be affected, by airframe or engine model (OpenAirDocs)
- FAA DRS: https://drs.faa.gov/browse/excelExternalWindow/7A39AC53B65D8EFC8625698B00764381.0001
- DRS record last changed: November 21, 2025
- Page: https://openairdocs.org/ad/51-23-03

## The airworthiness directive

51-23-03 PIPER: Applies to Model PA-16 Aircraft, Serial Numbers 16-1 and Up; PA-20 Aircraft, Serial Numbers 20-1 Through 20-802; and PA-22 Aircraft, Serial Numbers 22-1 Through 22-348.

Compliance required as soon as possible, but not later than October 15, 1951.

Install insulators of sufficient area inside the battery box cover over the battery terminals to positively prevent a metallic contact between the wing nuts or terminals and cover. Hard fiber rubber or phenolic insulating materials 1/16-inch minimum thickness may be used.

(Piper Service Bulletin No. 118 covers this same subject.)

## Affected data sheets (3) (OpenAirDocs)

The type certificate data sheets whose models the AD names.

- [TCDS 1A1](https://openairdocs.org/tcds/1A1): Piper Aircraft Inc.; names 1 of 2 models: PA-16
- [TCDS 1A4](https://openairdocs.org/tcds/1A4): Piper Aircraft Inc.; names 1 of 6 models: PA-20
- [TCDS 1A6](https://openairdocs.org/tcds/1A6): Piper Aircraft Inc.; names 1 of 8 models: PA-22

## Registered aircraft it may apply to (OpenAirDocs)

Matched by airframe and engine model; the AD's applicability may narrow it by serial number, part number or equipment.

- Aircraft: 829 (829 by airframe model, 0 by engine model)
- Makers: Piper 829

Models with the most aircraft:

- [Piper PA-22](https://openairdocs.org/model/piper-pa-22): 277 aircraft (airframe model)
- [Piper PA-16](https://openairdocs.org/model/piper-pa-16): 276 aircraft (airframe model)
- [Piper PA-20](https://openairdocs.org/model/piper-pa-20): 276 aircraft (airframe model)

All 3 models: https://openairdocs.org/ad/51-23-03/models.md
Every aircraft: https://openairdocs.org/ad/51-23-03/aircraft.md

Its text cites no advisory circulars or STCs.

---
OpenAirDocs.org is an independent research project of [Contrail Labs](https://contraillabs.com/). It is not affiliated with the FAA or the NTSB. Source documents are U.S. government works in the public domain.