UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                   FORM 6-K

                        REPORT OF FOREIGN PRIVATE ISSUER
                       PURSUANT TO RULE 13a-16 OR 15d-16
                     UNDER THE SECURITIES EXCHANGE ACT OF 1934




                       For the month of August, 2004

                                 SPIRENT plc
     _____________________________________________________________________
                (Translation of registrant's name into English)

  Spirent House, Crawley Business Quarter, Fleming Way, Crawley, West Sussex
                                RH10 9QL, UK.
     _____________________________________________________________________
                    (Address of principal executive offices)


Indicate by check mark whether the registrant files or will file annual reports
under cover Form 20-F or Form 40-F.

                         Form 20-F    X         Form 40-F.....

Indicate by check mark whether the registrant by furnishing the information
contained in this Form is also thereby furnishing the information to the
Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934.

                               Yes .....        No     X

If "Yes" is marked, indicate below the file number assigned to the registrant
in connection with Rule 12g3-2(b): 82- ________



                                                            834 - 16 August 2004



                                  SPIRENT PLC

                      Sale of Aerospace software Business


Spirent plc (LSE: SPT; NYSE: SPM), a leading communications technology company,
announces that it has sold its aerospace maintenance, repair and overhaul
software business (MRO) from within its Systems group for a cash consideration
of $5.35 million (approximately GBP2.9 million).


MRO,  with  operations  in San Diego,  California  and  Yeovil,  Somerset,  is a
supplier of ground-based logistics support and maintenance,  repair and overhaul
software systems for the civil and military aviation markets.  In the year to 31
December 2003, MRO had sales of GBP8.7 million.


The net  proceeds  of the sale  will be used to  pre-pay  $5.0  million  (GBP2.7
million)  of  Spirent's  senior  notes.  After the  application  of the net sale
proceeds   Spirent  will  have  $124.8  million   (GBP68.6   million)  of  notes
outstanding.


Anders Gustafsson, Chief Executive, said:


"MRO has an established position in its market and should have every opportunity
to move forward under its new ownership.  The sale of MRO is the last in the
series of strategic divestments of our aerospace businesses."


                                    - ends -




Enquiries


                                                               
Anders Gustafsson, Chief Executive    Spirent plc             +44 (0)1293 767676
Eric Hutchinson, Finance Director

Investor Relations
Catherine Nash                        Spirent plc             +44 (0)1293 767676

Media
Jon Coles/Rupert Young               Brunswick               +44 (0)20 7404 5959



About Spirent



Spirent is a leading communications technology company focused on delivering
innovative systems and services to meet the needs of customers worldwide.  We
are a global provider of performance analysis and service assurance solutions
that enable the development and deployment of next-generation networking
technologies such as broadband services, Internet telephony, 3G wireless and web
applications and security testing.  Our Network Products business is a developer
and manufacturer of innovative solutions for fastening, identification,
protection and connectivity in electrical and communications networks marketed
under the global brand HellermannTyton.  The Systems group comprises PG Drives
Technology which develops power control systems for specialist electrical
vehicles in the mobility and industrial markets.  Further information about
Spirent plc can be found at www.spirent.com



Spirent Ordinary shares are traded on the London Stock Exchange (ticker: SPT)
and on the New York Stock Exchange (ticker: SPM; CUSIP number: 84856M209) in the
form of American Depositary Shares (ADS), represented by American Depositary
Receipts, with one ADS representing four Ordinary shares.



Spirent and the Spirent logo are trademarks or registered trademarks of Spirent
plc.  All other trademarks or registered trademarks mentioned herein are held by
their respective companies.  All rights reserved.



This press release may contain forward-looking statements that are based on
current expectations or beliefs, as well as assumptions about future events.  By
their nature, forward-looking statements are inherently predictive, speculative
and involve risk and uncertainty because they relate to events and depend on
circumstances that will occur in the future.  You should not place undue
reliance on these forward-looking statements, which are not a guarantee of
future performance and are subject to factors that could cause our actual
results to differ materially from those expressed or implied by these
statements.  These risks include the risks described from time to time in
Spirent plc's Securities and Exchange Commission periodic reports and filings.
The Company undertakes no obligation to update any forward-looking statements
contained in this press release, whether as a result of new information, future
events or otherwise.




                                   Signatures

Pursuant to the requirements of the Securities Exchange Act of 1934, the
registrant has duly caused this report to be signed on its behalf by the
undersigned, thereunto duly authorized.

                                               ______LUKE THOMAS______

                                                     (Registrant)

Date 16 August 2004                         By   ____/s/ Luke Thomas____

                                                    (Signature)*