Service Information Letter #A-141 - Hartzell Engine Technologies

Service Information Letter 

Letter A-141 

2900 Selma Highway 

Montgomery, AL 36108 USA 

Tel: 334-386-5400 Fax: 334-386-5450 

Direct Drive Starter Motor 

Torque & Drive Shaft Tolerance 

1. Planning Information 

A. Effectivity 

(1) Hartzell Engine Technologies LLC (HET), formerly Kelly Aerospace Energy Systems, LLC 

(KAES), direct drive starter motor, models: ES646238-2, ES646238-3, ES646275-1, 

MCL-6501, and MHJ-4003. All serial numbers. The affected starters are FAA PMA 

approved. 

CAUTION: DO NOT USE OBSOLETE OR OUTDATED INFORMATION. PERFORM ALL 

INSPECTIONS OR WORK IN ACCORDANCE WITH THE MOST RECENT 

REVISION OF THE OE-A2 OVERHAUL & MAINTENANCE MANUAL (MM) AND 

THIS SERVICE INFORMATION LETTER (SIL). INFORMATION CONTAINED IN 

THE MM AND THE SIL MAY BE SIGNIFICANTLY CHANGED FROM EARLIER 

REVISIONS. USE OF OBSOLETE INFORMATION MAY CREATE AN UNSAFE 

CONDITION THAT MAY RESULT IN DEATH, SERIOUS BODILY INJURY, AND/OR 

SUBSTANTIAL PROPERTY DAMAGE. REFER TO THE SIL AND MM INDEX FOR 

THE MOST RECENT REVISION LEVEL. 

B. Concurrent Requirements 

(1) None 

C. Reason 

(1) It has come to the attention of HET that only basic information regarding direct drive 

starter motor shaft end play is contained in the current OE-A2 Alternator and Starter 

Overhaul and Maintenance manual. 

(2) A binding or free condition may lead to a short service life or an inoperative starter 

when mounted to a starter drive adapter. 

(3) Regulatory action is not expected. 

D. Description 

(1) This Service Information Letter is being issued to provide service information to 

supplement the current OE-A2 Alternator and Starter Overhaul and Maintenance 

Manual until a revision can be made to add the technical information herein. 

(2) The conditions must be checked per this SIL prior to the installation of a starter. 

Rev. New: April 1/11 SIL A-141 

© 2011 - Hartzell Engine Technologies. - All rights reserved Page 1 of 8





Tel: 334-386-5400 Fax: 334-386-5450 



E. Compliance 

(1) Any time a new, rebuilt, or overhauled direct drive starter motor is installed on a 

starter drive adapter for an aircraft engine per the effectivity 1.A.(1). 

(2) Compliance of this Service Information Letter is recommended. 

F. Approval 

(1) FAA approval has been obtained on technical data in this publication that affects type 

design. 

G. Manpower 

(1) No additional man hours are required for this pre-installation instruction. 

H. Weight and Balance 

(1) No change. 

I. Electrical Load Data 

(1) No change. 

J. References 

(1) Hartzell Engine Technologies OE-A2 Overhaul & Maintenance Manual. 

(2) Aircraft Maintenance Manual. 

(3) Teledyne Continental Motors Maintenance Manual. 

K. Other Publications Affected 

(1) Hartzell Engine Technologies OE-A2 Overhaul Manual. 

2. Material Information 

A. None. 







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3. Accomplishment Instructions 

A. Observe Figure 1 for the starter drive shaft specifications and torque. 

Typical Starter 

for Gear Drive 

System 

Figure 1 - Starter Drive Shaft Specifications 

B. Drive shaft “at rest” torque check 

(1) Check the drive shaft “at rest” torque first, as any discrepancy found will require 

repair or overhaul of the starter. 

(2) Rotate the the starter drive shaft by hand several turns clockwise (CW) as viewed from 

the drive end. 

(3) Use a suitable tool with a properly calibrated inch-pound torque wrench to check 

torque. A tool can be made using an appropriately sized clevis bolt with a nut tightened 

securely on the thread end. 

(4) Rotate the inch-pound torque wrench clockwise (CW) through 360˚ or more. The 

torque indication must be 5 inch pounds or less. The starter must be repaired or 

overhauled if rotational torque is higher. 

C. Drive shaft position check 

(1) Check the position of the drive shaft with respect to the housing for min and max 

tolerance using a dial indicator. Any style of dial indicator set up is permissible 

provided that the indicator reads to a minimum of .001 inch resolution. 







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(2) The set up requires the starter be held vertically with the drive shaft up and then 

vertically with the drive shaft down. 

(a) 

(b) 

Placing the starter vertical with the drive shaft up allows a check of the length of 

the drive shaft from the starter mounting flange. 

Placing the starter vertical with the drive shaft down allows a check of the drive 

shaft end play by measurement and calculation. 

(3) Check the starter drive shaft minimum length by setting the starter on blocks vertically 

with the drive shaft up. 

(a) 

(b) 

(b) 

Size the blocks of equal measure and width so the starter is stable. 

Place the bottom side of the mounting flange (flange with holes) on to tall blocks. 

Tap gently on the drive shaft with a plastic mallet. 

(4) Place the dial indicator on the flange surface which will be attached to the engine 

starter drive adapter, zero the indicator. See Fig. 2. 

Figure 2 - Set Dial at Zero on Flange 







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(5) Place the dial indicator on the apex of the drive shaft and record measurement. 

See Fig. 3. 

(a) 

The measurement recorded in step 3.C.(5) must fall in between .580 inch and 

.630 inch inclusive of the starter end play allowance. 

Figure 3 - Record Number at Apex of Shaft 







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D. Drive shaft maximum length check 

(1) Check the starter drive shaft maximum length by setting the starter vertically with the 

drive shaft down. 

(a) 

(b) 

(c) 

(d) 

Rotate the drive shaft by hand through one turn. 

Size the blocks of equal measure and width so the starter is stable. 

Place the mounting flange (flange with holes facing starter drive) on the blocks. 

Tap gently on the drive shaft rear cover with a plastic mallet. 

(2) Place the dial indicator on the flange surface which will be attached to the drive 

adapter, zero the indicator. See Fig. 4. 

Figure 4 - Set Dial at Zero on Flange 







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(3) Place the dial indicator on the apex of the drive shaft and record measurement. 

See Fig. 5. 

(a) 

The measurement recorded in step 3.D.(6) must fall in between .580 inch and 

.630 inch which is inclusive of the starter end play allowance. 

Figure 5 - Record Number at Top of Shaft 

E. End play determination 

(1) Determine if the starter falls into the allowable end play measurement by making a 

calculation. This is done by taking the maximum measurement found in step 

3.D.(6) and subtracting the minimum measurement found in step 3.C.(5). 

(a) 

For example, if the shaft maximum measurement from step 3.D.(6) was .610 inch 

and the minimum measurement from step 3.C.(5) was .585 inch then subtracting 

.585 inch from the .610 inch will result in .025 inch end play. This is acceptable 

as the allowable end play range is .005 to .050 inch. 

(2) If the starter drive shaft end play is out of allowable range of .005 to .050 inch or the 

drive shaft length is beyond the min .580 or max .630 inch, repair or overhaul of the 

starter is recommended. Do not install starters outside of these limits on any 

starter drive or application. 

F. This inspection check does not require a log book entry unless the starter has been 

replaced, repaired, or overhauled. 







Tel: 334-386-5400 Fax: 334-386-5450 



4. Warranty Statement 

A. The sole warranty for the actions within this service information letter are contained in the 

HET Limited Warranty Policy issued with the purchase of each new or rebuilt starter (see 

terms and conditions therein). 

B. Issuance of this service information letter in no way constitutes an implied or expressed 

warranty of any kind. 

C. This publication does not imply or state any responsibility for the workmanship of any person 

or entity performing work or maintenance on the starter or aircraft electrical system. 

5. Contact Information 

A. All communications regarding this service information letter, must be placed either through 

Hartzell Engine Technologies Technical Support at (888) 461-6077 or via Fax (334) 386-5450. 

For the Warranty department, (334) 386-5441. 

B. Written communications must be placed through Hartzell Engine Technologies Technical 

Support, 2900 Selma Highway, Montgomery, AL 36108, USA. 

C. If E-mail communication is desired, go to our website: http://www.hartzellenginetech.com 

and select "contact" and follow the instructions.

Service Information Letter #A-141 - Hartzell Engine Technologies

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