             United States Court of Appeals
                         FOR THE EIGHTH CIRCUIT



                              ___________

                              No. 96-3605
                              ___________

                                *
Air Evac EMS, Inc.              *
                                *
     Appellee,                  *
                                * Appeal from the United States
     v.                         * District Court for the Western
                                * District of Missouri
Aeronautical Accessories,       *
Inc., Edwards & Associates,     *   [UNPUBLISHED]
Inc.,                           *
                                *
     Appellants.                *
                          _____________

                       Submitted:   June 13,1997

                           Filed: September 5,1997
                             ______________

Before RICHARD S. ARNOLD, Chief Judge, BEEZER1 and WOLLMAN,
Circuit Judges
                          _____________

BEEZER, Circuit Judge:


        Defendants Aeronautical Accessories, Inc. (“Aeronautical”) and
Edwards & Associates, Inc. (“Edwards”) appeal the district court’s
jury verdict in favor of plaintiff Air Evac EMS (“Air Evac”) in Air
Evac’s product liability action.     We have jurisdiction pursuant to
28 U.S.C. § 1291.      We affirm in part and reverse and remand in
part.



        1
     The Honorable Robert R. Beezer, United States Circuit Judge
for the Ninth Circuit, sitting by designation.
                                    I


     This   product   liability   action    arises    from   a   helicopter
accident.    Early in the morning on April 1, 1988, pilot David
Short, flying a Bell helicopter to an accident scene, decided to
abort the mission due to weather conditions.          The helicopter was
equipped with a “nightscanner” light, a rotating search light
mounted underneath the helicopter.           When Short activated the
nightscanner in order to check his forward visibility, the glare
from the light temporarily blinded him.        He attempted to turn off
the nightscanner, but the light failed to extinguish, causing Short
to lose visual reference to the ground.      Short then lost control of
the helicopter and it crashed into a field near Springfield,
Missouri.   Short and his passengers sustained injuries.


     The owner of the helicopter, Air Evac, brought this action
against Edwards, the installer of the nightscanner system, and
Aeronautical, a previous owner of the helicopter, along with other
defendants who have since been dismissed.            The jury returned a
verdict in favor of Air Evac, holding that Short was ten percent at
fault and the defendants ninety percent at fault.            The district
court awarded Air Evac $1,076,323.36 plus pre-judgment and post-
judgment interest.     The court denied the defendants’ motion to
alter or amend the judgment.      This timely appeal followed.


                                   II


     Defendants first argue that the district court abused its
discretion in admitting the testimony of Air Evac’s expert witness
Michael Postiglione.    See Peitzmeier v. Hennessy Indus., Inc., 97
F.3d 293, 296 (8th Cir. 1996) (reviewing admission of expert
testimony for abuse of discretion).        Defendants contend that




                                    2
Postiglione's testimony is inadmissible under Daubert v. Merrell
Dow Pharmaceuticals, Inc., 509 U.S. 579 (1993).


      Postiglione testified that he found visual evidence that the
contact points on the relay of the nightscanner had welded; other
experts testified that they could not detect evidence of welding
either through visual observation or with the use of a scanning
electron microscope.     If such welding occurred, it would cause the
light to remain illuminated even after the pilot moved the switch
into the "off" position.


     Defendants allege that Postiglione’s testimony is inadmissible
because he based his conclusion on visual inspection alone, rather
than employing   other    methods   of   inspection   as   did    the   other
experts.   But weakness in the factual basis of expert testimony
goes to the weight, and not the admissibility, of that testimony.
Loudermill v. Dow Chem. Co., 863 F.2d 566, 570 (8th Cir. 1988)
("[a]s a   general rule, the factual basis of an expert opinion goes
to the credibility of the testimony, not the admissibility, and it
is up to the opposing party to examine the factual basis for the
opinion in cross-examination"); see also Fed. R. Evid.           703.   “Only
if an expert's opinion is so fundamentally unsupported that it can
offer no assistance to the jury must such testimony be excluded.”
Hose v. Chicago Northwestern Transp. Co., 70 F.3d 968, 974 (8th
Cir. 1995) (internal quotation omitted).
     The    district     court   addressed     the    admissibility       of
Postiglione's testimony in its denial of defendants' motion for
summary judgment.      The court noted that Postiglione's opinion was
not solely based upon visual inspection but also upon his analysis
of the testimony of others and his experience with electrical
components and relays.        Further, we note that the defendants
presented no evidence that the general practice of inspecting an
electrical relay for malfunction excludes visual observation.            The



                                    3
district court did not abuse its discretion in admitting the expert
testimony; it was the jury’s province to weigh the credibility of
Postiglione’s testimony.


                                       III


        Defendants next argue that the district court abused its
discretion in admitting evidence of the failures of nightscanners
that contained relays different from the relay in the nightscanner
at issue.      We review the district court's ruling on admissibility
of evidence for an abuse of discretion.          United States v. Mendoza,
85 F.3d 1347, 1351 (8th Cir. 1996).


     A primary evidentiary issue at trial concerned whether the
relay in the nightscanner could accommodate the in-rush current
passing through it without causing the light to remain illuminated
after    the   unit   was   switched    into   the   "off"    position.   The
nightscanner at issue was a Symbolic Display assembly, containing
a mechanical, 60-amp relay, labeled an “MB3D” relay.              Defendants'
expert testified that this relay could accommodate the in-rush
current.    The district court allowed Air Evac to introduce evidence
concerning     the    failure   of   nightscanners    which   used   Glare-Ban
assemblies.     Glare-Ban assemblies contain printed circuit contact
70-amp relays.        The evidence established that Symbolic Display
assemblies and Glare-Ban assemblies are interchangeable, and thus,
are subject to the same in-rush current.
     Because Glare-Ban and Symbolic Display assemblies contain
different relays, the defendants argue that the evidence relating
to failures of nightscanners containing Glare-Ban assemblies is not
substantially similar to the evidence concerning the failure of the
nightscanner used by Air Evac.          See McKnight v. Johnson Controls,
Inc., 36 F.3d 1396, 1410 (8th Cir. 1994) (evidence of other
accidents is admissible only if the other accident is substantially



                                        4
similar to the accident at issue).                 As the district court noted,
however,    the       evidence      of     the    failures    of    the     Glare-Ban
nightscanners was relevant both: (1) to impeach the testimony that
the 60-amp relay could handle the in-rush current and (2) to
establish that the defendants' engineer was negligent in not
adequately testing the MB3D relay to ensure it could accommodate
the in-rush current before installing that relay into the Symbolic
Displays nightscanner.              The district court did not abuse its
discretion in admitting the evidence concerning the failure of the
Glare-Ban nightscanners.


                                           IV


       Defendants also assert that the district court erred in
admitting evidence of the failures of three other Symbolic Display
nightscanners which contained MB3D relays.                    Defendants offer no
argument supporting this claim other than stating that the failures
were too remote in time to be of probative value.                         Defendants’
argument can be characterized as a claim that the evidence should
not have been permitted under Federal Rule of Evidence 403.                    Under
this rule, a District Court is permitted to exclude relevant
evidence "if its probative value is substantially outweighed by the
danger of unfair prejudice, confusion of the issues, or misleading
the jury, or by considerations of undue delay [or] waste of time."
Fed.   R.   Evid.     403.     We   will    not    reverse   a   district    court's
determination respecting the admissibility of evidence under Rule
403    absent     a    clear     and     prejudicial    abuse       of    discretion.
International Travel Arrangers v. NWA, Inc. 991 F.2d 1389, 1400
(8th Cir. 1993).
       Although the subsequent failures of other Symbolic Display
nightscanners occurred between five and eight years after the Air
Evac   accident,      the    district      court    found    that   the    subsequent
failures were substantially similar to the failure of the



                                            5
nightscanner     used   by   Air     Evac,    and,    thus    the    evidence         had
significant probative value.            For example, the other Symbolic
Display nightscanners that subsequently failed had configurations
and     modifications   identical      to     the    nightscanner          at    issue.
Moreover, evidence was presented that on each failed Symbolic
Display nightscanner the light tended to remain illuminated after
being turned into the “off” position.              Evidence of other accidents
can be used to prove causation.             McKnight, 36 F.3d at 1410.                The
district court did not abuse its discretion.


                                        V


        Next, defendants contend that the district court erred in
giving the jury a "negligent failure to warn" instruction.                            We
review jury instructions for abuse of discretion.                       Karcher v.
Emerson Elec. Co., 94 F.3d 502, 510 (8th Cir. 1996), cert. denied,
117 S. Ct. 1693 (1997).         Under Missouri law, in order to prove
negligent     failure   to   warn,    the    plaintiff      must    show    that      the
defendant knew or had reason to know about the dangerous condition.
Morris v. Shell Oil Co., 467 S.W.2d 39, 42 (Mo. 1971) (adopting
Restatement (Second) of Torts § 388).              Air Evac presented evidence
that    the   defendants'    engineer:       (1)     knew    that    the        original
configuration of the nightscanner tended to remain activated even
after    being   switched    "off";    (2)    did    minimal       testing       of   his
modification to the nightscanner; and (3) did not test the amount
of current passing through the relay to ensure that the relay could
accommodate the current.           This evidence was sufficient for the
district court to submit the failure to warn instruction to the
jury.


                                       VI
       Defendants further argue that the district court erred in
denying their motion for a directed verdict and motion for new



                                        6
trial because Air Evac failed to establish causation.                 We review de
novo the district court's denial of a motion for judgment as a
matter of law, which includes a motion for a directed verdict.
McKnight, 36 F.3d at 1400.             We apply a much more deferential
standard in our review of a district court's denial of a motion for
a new trial:      "The [district] court's decision will not be reversed
by   a    court   of   appeals   in   the    absence     of   a    clear    abuse   of
discretion."      Lowe v. E.I. DuPont de NeMours & Co., 802 F.2d 310,
310-11 (8th Cir. 1986).


         Defendants allege that Air Evac's circumstantial evidence did
not "tend to exclude any other reasonable conclusion" for the cause
of the accident.        See Aetna Cas. and Sur. Co. v. General Elec. Co.,
758 F.2d 319, 322 (8th Cir. 1985) (under Missouri law, when
plaintiff relies on circumstantial evidence in product liability
case, evidence must tend to exclude other reasonable conclusions).
Defendants' argument relies on the exclusion of the testimony of
plaintiff's expert Postiglione.          As discussed above, Postiglione's
testimony was properly admitted.            Air Evac, therefore, did not rely
solely on circumstantial evidence to prove causation.                 The district
court did not err in denying defendants' motion for a directed
verdict and did not abuse its discretion in denying defendants'
motion for a new trial.


                                       VI


         Finally, defendants argue that the district court erroneously
awarded pre-      and    post-judgment       interest.        We   review    de   novo
questions of state law.          Kansas Pub. Employees Retirement Sys. v.
Blackwell, Sanders, Matheny, Weary & Lombardi, L.C., 114 F.3d 679,
687 (8th Cir. 1997).




                                         7
                                        A.


     Defendants        contest   the    award    of       pre-judgment   interest,
calculated from December 4, 1991 to May 5, 1995, on the property
damage claim.      Missouri Rev. Stat. §408.040(2) permits payment of
pre-judgment interest on tort claims, provided that:                       1) the
claimant demanded payment or offered a settlement, via certified
mail, and (2) the judgment obtained exceeds the amount demanded.
Pre-judgment interest is available from 60 days after the demand
was made until the date of judgment.


     Defendants argue that Air Evac's December 4, 1991 letter does
not meet these criteria because plaintiff did not send the letter
through certified mail and the judgment did not exceed the amount
demanded.     In awarding pre-judgment interest, the district court
reasoned that because the damages were liquidated, Air Evac was
entitled to pre-judgment interest from the date it sent its demand
letter.


     Because a plain reading of the statute does not support the
district court’s reasoning, we hold that the district court erred
in granting pre-judgment interest on the property damage claim.                 We
remand for a determination, in accordance with § 408.040, of the
proper pre-judgment interest to be paid, if any, on the property
damage claim.


                                        B.
     Defendants also contest the pre-judgment interest award on the
contribution claim.         Again, defendants argue that the district
court     failed   to    apply   §     408.040       to   its   determination   of
pre-judgment interest and instead improperly relied on case law
holding     that   a    liquidated     claim    is    subject    to   pre-judgment
interest.    The district court, however, correctly concluded that an



                                         8
action for contribution is not "grounded in tort" but rather is
more like a claim for unjust enrichment.         See Rowland v. Skaggs
Cos., 666 S.W.2d 770, 773 (Mo. 1984) (en banc).         As such, § 408.040
is inapplicable and pre-judgment interest is available from the
date plaintiffs first demanded payment on the contribution claim.
The district court did not err.


                                  C.


     Defendants next argue that the district court improperly
applied the Missouri pre-judgment statutory interest rate to the
post-judgment interest claim.     Defendants correctly state that 28
U.S.C. § 1961 is the applicable statute.         Section 1961 provides
that the federal interest rate applies to money judgments in any
civil   case.    Plaintiff   concedes   this   issue.      We   remand   for
recalculation of post-judgment interest in accordance with 28
U.S.C. § 1961.


AFFIRMED in part, REVERSED and REMANDED in part.



A true copy.

           Attest:

                 CLERK, U.S. COURT OF APPEALS, EIGHTH CIRCUIT.




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