SUBJECT: STABILATOR HORN ASSEMBLY INSPECTION

MODELS AFFECTED: SERIAL NUMBERS AFFECTED:

PA-24 Comanche 24-1 through 24-3687

PA-24-250 Comanche 24-1; 24-103 through 24-3687

PA-24-260 Comanche 24-3642 & 24-4000 through 24-5034

PA-24-400 Comanche 26-2 through 26-148

PA-30 Twin Comanche 30-1 through 30-2000

PA-39 Twin Comanche C/R 39-1 through 39-162

COMPLIANCE TIME: Perform a fi rst-time inspection of the Stabilator Horn Assembly upon reaching 

the initial one thousand (1000) hours of fl ight, with a recurring inspection to take 

place every one hundred (100) hours of operation thereafter. Installation of a new 

Stabilator Horn Assembly will relieve the repetitive inspection requirement, until 

the new Stabilator Horn reaches one thousand (1000) hours of operation. 

 The inspection schedule defi ned in this Service Bulletin shall apply until 

superseded by requirements added to the Service Manual.

APPROVAL: The technical content of this Service Bulletin has been shown to comply with the 

applicable Federal Aviation Regulations and is FAA approved.

PURPOSE: Reports have been received of cracks developing in the Stabilator Horn Assembly. 

Left uncorrected, this condition could cause separation of the Stabilator Horn 

from the Stabilator Torque Tube, leading to a reduction in pitch control.

 

INSTRUCTIONS:

1. Remove the Stabilator Horn Assembly (includes Stabilator Horn and the longitudinal Balance Weight Tube 

that is press-fi t into the Stabilator Horn) from the aircraft. Proper inspection will require the disassembly of the 

Stabilator Horn Assembly from the Balance Weight, Stabilator Control Cable, and Stabilator Torque Tube. Refer 

to the appropriate Piper Service Manual for specifi c procedures.

NOTE: Examine all hardware and components that are removed during the inspection procedure, and repair 

or replace on condition. 

NOTE: Since the Balance Weight Tube is press-fi t into the Stabilator Horn and bolted together through 

a close-tolerance hole that is match-drilled at the factory, disassembly of these two parts is not 

recommended, nor is it required to accomplish this inspection.

 SERVICE NO. 1189

 BULLETIN

PIPER CONSIDERS

COMPLIANCE MANDATORY

Piper Aircraft, Inc.

2926 Piper Drive

Vero Beach, Florida, U.S.A. 32960

Date: April 29, 2010 (S) (M)

 (OVER)

 ATA: 5510 
SERVICE BULLETIN NO. 1189 PAGE 2 of 3

INSTRUCTIONS: (continued)

2. Inspect the inside and outside of the Balance Weight Tube for signs of corrosion. No service limits exist for the 

outside diameter and wall thickness of this tube. Therefore, any measurable corrosion requires replacement of 

the Stabilator Horn Assembly.

3. Clean the inner surface of the Stabilator Horn with isopropyl alcohol, and perform dye penetrant inspection per 

AC 43.13-1B (Aircraft Inspection and Repair Manual), with specifi c emphasis on the areas denoted by heavy 

lines in Figure 1.

NOTE: When cracks occur, they have been found to originate at an inner surface of the Stabilator Horn, as 

shown in Figure 1. Therefore, removal of exterior paint is not required for inspection. However, the 

Stabilator Horn MUST be removed from the Stabilator Torque Tube, in order to gain visual access to 

these areas.

4. If cracking or corrosion is discovered in the Balance Weight Tube or Stabilator Horn, order and install a 

replacement Stabilator Horn Assembly. Refer to Table 1 for the applicable part number.

NOTE: The Horn Assemblies shown in Table 1 are supplied with a Stabilator Balance Block Tube that has 

(2) undersized holes common to the Stabilator Balance Weight, in order to provide a precise matchup with the existing Stabilator Balance Weight. Prior to installing the Horn Assembly in the aircraft, 

assemble the existing Stabilator Balance Weight to the new Horn Assembly, as follows: Slide the 

shaft of the Stabilator Balance Weight into the open end of the Stabilator Balance Block Tube. Align 

the (2) fastener holes in the shaft of the Stabilator Balance Weight with the undersized holes in the 

Stabilator Balance Block. Line ream the holes to a fi nal size of .251 to .249 inches in diameter, 2 

places. Install fasteners per the appropriate Illustrated Parts Catalog.

5. If no cracking or corrosion is discovered, clean inspection areas with isopropyl alcohol to remove dye penetrant. 

Reinstall all serviceable parts (Refer to the appropriate Piper Service Manual). At locations where paint was 

removed, apply two coats of epoxy primer. Treat bare metal surfaces with Dinitrol AV8 or CRC Protector 100 

Corrosion Inhibitor.

6. Make a logbook entry indicating compliance with this Service Bulletin and return aircraft to service.

Figure 1 

Lines indicate Inspection Area
SERVICE BULLETIN NO. 1189 PAGE 3 of 3

MATERIAL REQUIRED:

AVAILABILITY OF PARTS: Your Piper Service Facility.

EFFECTIVITY DATE: This Service Bulletin is effective as of release date.

SUMMARY: Applicable Factory Participation is limited to new aircraft in warranty at the time of 

compliance. Factory Participation will remain in effect for a period of time not to 

exceed 180 days from the date of this Service Bulletin.

Please contact your Factory Authorized Piper Service Facility to make arrangements for compliance with this 

Service Bulletin in accordance with the compliance time indicated.

NOTE: Please notify the factory of any address/ownership corrections. Changes should include aircraft 

model, serial number, current owner’s name and address.

 Corrections and/or changes should be directed to:

 PIPER AIRCRAFT, INC.

 Attn: Customer Service

 2926 Piper Drive

 Vero Beach, FL 32960

MODEL HORN ASSEMBLY AC S/N AFFECTED

PA-24 Comanche 20399-004 24-1 through 24-102

PA-24 Comanche 20399-005 24-103 through 24-3687

PA-24-250 Comanche 20399-004 24-1

PA-24-250 Comanche 20399-005 24-103 through 24-3687

PA-24-260 Comanche 20399-005 24-3642 through 24-5028

PA-24-400 Comanche 22882-003 26-2 through 26-148

PA-30 Twin Comanche 22882-003 30-2 through 30-2000

PA-39 Twin Comanche 22882-003 39-1 through 39-155

Table 1